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# orm/mapper.py
# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php
# mypy: allow-untyped-defs, allow-untyped-calls
"""Logic to map Python classes to and from selectables.
Defines the :class:`~sqlalchemy.orm.mapper.Mapper` class, the central
configurational unit which associates a class with a database table.
This is a semi-private module; the main configurational API of the ORM is
available in :class:`~sqlalchemy.orm.`.
"""
from __future__ import annotations
from collections import deque
from functools import reduce
from itertools import chain
import sys
import threading
from typing import Any
from typing import Callable
from typing import cast
from typing import Collection
from typing import Deque
from typing import Dict
from typing import FrozenSet
from typing import Generic
from typing import Iterable
from typing import Iterator
from typing import List
from typing import Mapping
from typing import Optional
from typing import Sequence
from typing import Set
from typing import Tuple
from typing import Type
from typing import TYPE_CHECKING
from typing import TypeVar
from typing import Union
import weakref
from . import attributes
from . import exc as orm_exc
from . import instrumentation
from . import loading
from . import properties
from . import util as orm_util
from ._typing import _O
from .base import _class_to_mapper
from .base import _parse_mapper_argument
from .base import _state_mapper
from .base import PassiveFlag
from .base import state_str
from .interfaces import _MappedAttribute
from .interfaces import EXT_SKIP
from .interfaces import InspectionAttr
from .interfaces import MapperProperty
from .interfaces import ORMEntityColumnsClauseRole
from .interfaces import ORMFromClauseRole
from .interfaces import StrategizedProperty
from .path_registry import PathRegistry
from .. import event
from .. import exc as sa_exc
from .. import inspection
from .. import log
from .. import schema
from .. import sql
from .. import util
from ..event import dispatcher
from ..event import EventTarget
from ..sql import base as sql_base
from ..sql import coercions
from ..sql import expression
from ..sql import operators
from ..sql import roles
from ..sql import TableClause
from ..sql import util as sql_util
from ..sql import visitors
from ..sql.cache_key import MemoizedHasCacheKey
from ..sql.elements import KeyedColumnElement
from ..sql.schema import Column
from ..sql.schema import Table
from ..sql.selectable import LABEL_STYLE_TABLENAME_PLUS_COL
from ..util import HasMemoized
from ..util import HasMemoized_ro_memoized_attribute
from ..util.typing import Literal
if TYPE_CHECKING:
from ._typing import _IdentityKeyType
from ._typing import _InstanceDict
from ._typing import _ORMColumnExprArgument
from ._typing import _RegistryType
from .decl_api import registry
from .dependency import DependencyProcessor
from .descriptor_props import CompositeProperty
from .descriptor_props import SynonymProperty
from .events import MapperEvents
from .instrumentation import ClassManager
from .path_registry import CachingEntityRegistry
from .properties import ColumnProperty
from .relationships import RelationshipProperty
from .state import InstanceState
from .util import ORMAdapter
from ..engine import Row
from ..engine import RowMapping
from ..sql._typing import _ColumnExpressionArgument
from ..sql._typing import _EquivalentColumnMap
from ..sql.base import ReadOnlyColumnCollection
from ..sql.elements import ColumnClause
from ..sql.elements import ColumnElement
from ..sql.selectable import FromClause
from ..util import OrderedSet
_T = TypeVar("_T", bound=Any)
_MP = TypeVar("_MP", bound="MapperProperty[Any]")
_Fn = TypeVar("_Fn", bound="Callable[..., Any]")
_WithPolymorphicArg = Union[
Literal["*"],
Tuple[
Union[Literal["*"], Sequence[Union["Mapper[Any]", Type[Any]]]],
Optional["FromClause"],
],
Sequence[Union["Mapper[Any]", Type[Any]]],
]
_mapper_registries: weakref.WeakKeyDictionary[_RegistryType, bool] = (
weakref.WeakKeyDictionary()
)
def _all_registries() -> Set[registry]:
with _CONFIGURE_MUTEX:
return set(_mapper_registries)
def _unconfigured_mappers() -> Iterator[Mapper[Any]]:
for reg in _all_registries():
yield from reg._mappers_to_configure()
_already_compiling = False
# a constant returned by _get_attr_by_column to indicate
# this mapper is not handling an attribute for a particular
# column
NO_ATTRIBUTE = util.symbol("NO_ATTRIBUTE")
# lock used to synchronize the "mapper configure" step
_CONFIGURE_MUTEX = threading.RLock()
@inspection._self_inspects
@log.class_logger
class Mapper(
ORMFromClauseRole,
ORMEntityColumnsClauseRole[_O],
MemoizedHasCacheKey,
InspectionAttr,
log.Identified,
inspection.Inspectable["Mapper[_O]"],
EventTarget,
Generic[_O],
):
"""Defines an association between a Python class and a database table or
other relational structure, so that ORM operations against the class may
proceed.
The :class:`_orm.Mapper` object is instantiated using mapping methods
present on the :class:`_orm.registry` object. For information
about instantiating new :class:`_orm.Mapper` objects, see
:ref:`orm_mapping_classes_toplevel`.
"""
dispatch: dispatcher[Mapper[_O]]
_dispose_called = False
_configure_failed: Any = False
_ready_for_configure = False
@util.deprecated_params(
non_primary=(
"1.3",
"The :paramref:`.mapper.non_primary` parameter is deprecated, "
"and will be removed in a future release. The functionality "
"of non primary mappers is now better suited using the "
":class:`.AliasedClass` construct, which can also be used "
"as the target of a :func:`_orm.relationship` in 1.3.",
),
)
def __init__(
self,
class_: Type[_O],
local_table: Optional[FromClause] = None,
properties: Optional[Mapping[str, MapperProperty[Any]]] = None,
primary_key: Optional[Iterable[_ORMColumnExprArgument[Any]]] = None,
non_primary: bool = False,
inherits: Optional[Union[Mapper[Any], Type[Any]]] = None,
inherit_condition: Optional[_ColumnExpressionArgument[bool]] = None,
inherit_foreign_keys: Optional[
Sequence[_ORMColumnExprArgument[Any]]
] = None,
always_refresh: bool = False,
version_id_col: Optional[_ORMColumnExprArgument[Any]] = None,
version_id_generator: Optional[
Union[Literal[False], Callable[[Any], Any]]
] = None,
polymorphic_on: Optional[
Union[_ORMColumnExprArgument[Any], str, MapperProperty[Any]]
] = None,
_polymorphic_map: Optional[Dict[Any, Mapper[Any]]] = None,
polymorphic_identity: Optional[Any] = None,
concrete: bool = False,
with_polymorphic: Optional[_WithPolymorphicArg] = None,
polymorphic_abstract: bool = False,
polymorphic_load: Optional[Literal["selectin", "inline"]] = None,
allow_partial_pks: bool = True,
batch: bool = True,
column_prefix: Optional[str] = None,
include_properties: Optional[Sequence[str]] = None,
exclude_properties: Optional[Sequence[str]] = None,
passive_updates: bool = True,
passive_deletes: bool = False,
confirm_deleted_rows: bool = True,
eager_defaults: Literal[True, False, "auto"] = "auto",
legacy_is_orphan: bool = False,
_compiled_cache_size: int = 100,
):
r"""Direct constructor for a new :class:`_orm.Mapper` object.
The :class:`_orm.Mapper` constructor is not called directly, and
is normally invoked through the
use of the :class:`_orm.registry` object through either the
:ref:`Declarative <orm_declarative_mapping>` or
:ref:`Imperative <orm_imperative_mapping>` mapping styles.
.. versionchanged:: 2.0 The public facing ``mapper()`` function is
removed; for a classical mapping configuration, use the
:meth:`_orm.registry.map_imperatively` method.
Parameters documented below may be passed to either the
:meth:`_orm.registry.map_imperatively` method, or may be passed in the
``__mapper_args__`` declarative class attribute described at
:ref:`orm_declarative_mapper_options`.
:param class\_: The class to be mapped. When using Declarative,
this argument is automatically passed as the declared class
itself.
:param local_table: The :class:`_schema.Table` or other
:class:`_sql.FromClause` (i.e. selectable) to which the class is
mapped. May be ``None`` if this mapper inherits from another mapper
using single-table inheritance. When using Declarative, this
argument is automatically passed by the extension, based on what is
configured via the :attr:`_orm.DeclarativeBase.__table__` attribute
or via the :class:`_schema.Table` produced as a result of
the :attr:`_orm.DeclarativeBase.__tablename__` attribute being
present.
:param polymorphic_abstract: Indicates this class will be mapped in a
polymorphic hierarchy, but not directly instantiated. The class is
mapped normally, except that it has no requirement for a
:paramref:`_orm.Mapper.polymorphic_identity` within an inheritance
hierarchy. The class however must be part of a polymorphic
inheritance scheme which uses
:paramref:`_orm.Mapper.polymorphic_on` at the base.
.. versionadded:: 2.0
.. seealso::
:ref:`orm_inheritance_abstract_poly`
:param always_refresh: If True, all query operations for this mapped
class will overwrite all data within object instances that already
exist within the session, erasing any in-memory changes with
whatever information was loaded from the database. Usage of this
flag is highly discouraged; as an alternative, see the method
:meth:`_query.Query.populate_existing`.
:param allow_partial_pks: Defaults to True. Indicates that a
composite primary key with some NULL values should be considered as
possibly existing within the database. This affects whether a
mapper will assign an incoming row to an existing identity, as well
as if :meth:`.Session.merge` will check the database first for a
particular primary key value. A "partial primary key" can occur if
one has mapped to an OUTER JOIN, for example.
:param batch: Defaults to ``True``, indicating that save operations
of multiple entities can be batched together for efficiency.
Setting to False indicates
that an instance will be fully saved before saving the next
instance. This is used in the extremely rare case that a
:class:`.MapperEvents` listener requires being called
in between individual row persistence operations.
:param column_prefix: A string which will be prepended
to the mapped attribute name when :class:`_schema.Column`
objects are automatically assigned as attributes to the
mapped class. Does not affect :class:`.Column` objects that
are mapped explicitly in the :paramref:`.Mapper.properties`
dictionary.
This parameter is typically useful with imperative mappings
that keep the :class:`.Table` object separate. Below, assuming
the ``user_table`` :class:`.Table` object has columns named
``user_id``, ``user_name``, and ``password``::
class User(Base):
__table__ = user_table
__mapper_args__ = {'column_prefix':'_'}
The above mapping will assign the ``user_id``, ``user_name``, and
``password`` columns to attributes named ``_user_id``,
``_user_name``, and ``_password`` on the mapped ``User`` class.
The :paramref:`.Mapper.column_prefix` parameter is uncommon in
modern use. For dealing with reflected tables, a more flexible
approach to automating a naming scheme is to intercept the
:class:`.Column` objects as they are reflected; see the section
:ref:`mapper_automated_reflection_schemes` for notes on this usage
pattern.
:param concrete: If True, indicates this mapper should use concrete
table inheritance with its parent mapper.
See the section :ref:`concrete_inheritance` for an example.
:param confirm_deleted_rows: defaults to True; when a DELETE occurs
of one more rows based on specific primary keys, a warning is
emitted when the number of rows matched does not equal the number
of rows expected. This parameter may be set to False to handle the
case where database ON DELETE CASCADE rules may be deleting some of
those rows automatically. The warning may be changed to an
exception in a future release.
:param eager_defaults: if True, the ORM will immediately fetch the
value of server-generated default values after an INSERT or UPDATE,
rather than leaving them as expired to be fetched on next access.
This can be used for event schemes where the server-generated values
are needed immediately before the flush completes.
The fetch of values occurs either by using ``RETURNING`` inline
with the ``INSERT`` or ``UPDATE`` statement, or by adding an
additional ``SELECT`` statement subsequent to the ``INSERT`` or
``UPDATE``, if the backend does not support ``RETURNING``.
The use of ``RETURNING`` is extremely performant in particular for
``INSERT`` statements where SQLAlchemy can take advantage of
:ref:`insertmanyvalues <engine_insertmanyvalues>`, whereas the use of
an additional ``SELECT`` is relatively poor performing, adding
additional SQL round trips which would be unnecessary if these new
attributes are not to be accessed in any case.
For this reason, :paramref:`.Mapper.eager_defaults` defaults to the
string value ``"auto"``, which indicates that server defaults for
INSERT should be fetched using ``RETURNING`` if the backing database
supports it and if the dialect in use supports "insertmanyreturning"
for an INSERT statement. If the backing database does not support
``RETURNING`` or "insertmanyreturning" is not available, server
defaults will not be fetched.
.. versionchanged:: 2.0.0rc1 added the "auto" option for
:paramref:`.Mapper.eager_defaults`
.. seealso::
:ref:`orm_server_defaults`
.. versionchanged:: 2.0.0 RETURNING now works with multiple rows
INSERTed at once using the
:ref:`insertmanyvalues <engine_insertmanyvalues>` feature, which
among other things allows the :paramref:`.Mapper.eager_defaults`
feature to be very performant on supporting backends.
:param exclude_properties: A list or set of string column names to
be excluded from mapping.
.. seealso::
:ref:`include_exclude_cols`
:param include_properties: An inclusive list or set of string column
names to map.
.. seealso::
:ref:`include_exclude_cols`
:param inherits: A mapped class or the corresponding
:class:`_orm.Mapper`
of one indicating a superclass to which this :class:`_orm.Mapper`
should *inherit* from. The mapped class here must be a subclass
of the other mapper's class. When using Declarative, this argument
is passed automatically as a result of the natural class
hierarchy of the declared classes.
.. seealso::
:ref:`inheritance_toplevel`
:param inherit_condition: For joined table inheritance, a SQL
expression which will
define how the two tables are joined; defaults to a natural join
between the two tables.
:param inherit_foreign_keys: When ``inherit_condition`` is used and
the columns present are missing a :class:`_schema.ForeignKey`
configuration, this parameter can be used to specify which columns
are "foreign". In most cases can be left as ``None``.
:param legacy_is_orphan: Boolean, defaults to ``False``.
When ``True``, specifies that "legacy" orphan consideration
is to be applied to objects mapped by this mapper, which means
that a pending (that is, not persistent) object is auto-expunged
from an owning :class:`.Session` only when it is de-associated
from *all* parents that specify a ``delete-orphan`` cascade towards
this mapper. The new default behavior is that the object is
auto-expunged when it is de-associated with *any* of its parents
that specify ``delete-orphan`` cascade. This behavior is more
consistent with that of a persistent object, and allows behavior to
be consistent in more scenarios independently of whether or not an
orphan object has been flushed yet or not.
See the change note and example at :ref:`legacy_is_orphan_addition`
for more detail on this change.
:param non_primary: Specify that this :class:`_orm.Mapper`
is in addition
to the "primary" mapper, that is, the one used for persistence.
The :class:`_orm.Mapper` created here may be used for ad-hoc
mapping of the class to an alternate selectable, for loading
only.
.. seealso::
:ref:`relationship_aliased_class` - the new pattern that removes
the need for the :paramref:`_orm.Mapper.non_primary` flag.
:param passive_deletes: Indicates DELETE behavior of foreign key
columns when a joined-table inheritance entity is being deleted.
Defaults to ``False`` for a base mapper; for an inheriting mapper,
defaults to ``False`` unless the value is set to ``True``
on the superclass mapper.
When ``True``, it is assumed that ON DELETE CASCADE is configured
on the foreign key relationships that link this mapper's table
to its superclass table, so that when the unit of work attempts
to delete the entity, it need only emit a DELETE statement for the
superclass table, and not this table.
When ``False``, a DELETE statement is emitted for this mapper's
table individually. If the primary key attributes local to this
table are unloaded, then a SELECT must be emitted in order to
validate these attributes; note that the primary key columns
of a joined-table subclass are not part of the "primary key" of
the object as a whole.
Note that a value of ``True`` is **always** forced onto the
subclass mappers; that is, it's not possible for a superclass
to specify passive_deletes without this taking effect for
all subclass mappers.
.. seealso::
:ref:`passive_deletes` - description of similar feature as
used with :func:`_orm.relationship`
:paramref:`.mapper.passive_updates` - supporting ON UPDATE
CASCADE for joined-table inheritance mappers
:param passive_updates: Indicates UPDATE behavior of foreign key
columns when a primary key column changes on a joined-table
inheritance mapping. Defaults to ``True``.
When True, it is assumed that ON UPDATE CASCADE is configured on
the foreign key in the database, and that the database will handle
propagation of an UPDATE from a source column to dependent columns
on joined-table rows.
When False, it is assumed that the database does not enforce
referential integrity and will not be issuing its own CASCADE
operation for an update. The unit of work process will
emit an UPDATE statement for the dependent columns during a
primary key change.
.. seealso::
:ref:`passive_updates` - description of a similar feature as
used with :func:`_orm.relationship`
:paramref:`.mapper.passive_deletes` - supporting ON DELETE
CASCADE for joined-table inheritance mappers
:param polymorphic_load: Specifies "polymorphic loading" behavior
for a subclass in an inheritance hierarchy (joined and single
table inheritance only). Valid values are:
* "'inline'" - specifies this class should be part of
the "with_polymorphic" mappers, e.g. its columns will be included
in a SELECT query against the base.
* "'selectin'" - specifies that when instances of this class
are loaded, an additional SELECT will be emitted to retrieve
the columns specific to this subclass. The SELECT uses
IN to fetch multiple subclasses at once.
.. versionadded:: 1.2
.. seealso::
:ref:`with_polymorphic_mapper_config`
:ref:`polymorphic_selectin`
:param polymorphic_on: Specifies the column, attribute, or
SQL expression used to determine the target class for an
incoming row, when inheriting classes are present.
May be specified as a string attribute name, or as a SQL
expression such as a :class:`_schema.Column` or in a Declarative
mapping a :func:`_orm.mapped_column` object. It is typically
expected that the SQL expression corresponds to a column in the
base-most mapped :class:`.Table`::
class Employee(Base):
__tablename__ = 'employee'
id: Mapped[int] = mapped_column(primary_key=True)
discriminator: Mapped[str] = mapped_column(String(50))
__mapper_args__ = {
"polymorphic_on":discriminator,
"polymorphic_identity":"employee"
}
It may also be specified
as a SQL expression, as in this example where we
use the :func:`.case` construct to provide a conditional
approach::
class Employee(Base):
__tablename__ = 'employee'
id: Mapped[int] = mapped_column(primary_key=True)
discriminator: Mapped[str] = mapped_column(String(50))
__mapper_args__ = {
"polymorphic_on":case(
(discriminator == "EN", "engineer"),
(discriminator == "MA", "manager"),
else_="employee"),
"polymorphic_identity":"employee"
}
It may also refer to any attribute using its string name,
which is of particular use when using annotated column
configurations::
class Employee(Base):
__tablename__ = 'employee'
id: Mapped[int] = mapped_column(primary_key=True)
discriminator: Mapped[str]
__mapper_args__ = {
"polymorphic_on": "discriminator",
"polymorphic_identity": "employee"
}
When setting ``polymorphic_on`` to reference an
attribute or expression that's not present in the
locally mapped :class:`_schema.Table`, yet the value
of the discriminator should be persisted to the database,
the value of the
discriminator is not automatically set on new
instances; this must be handled by the user,
either through manual means or via event listeners.
A typical approach to establishing such a listener
looks like::
from sqlalchemy import event
from sqlalchemy.orm import object_mapper
@event.listens_for(Employee, "init", propagate=True)
def set_identity(instance, *arg, **kw):
mapper = object_mapper(instance)
instance.discriminator = mapper.polymorphic_identity
Where above, we assign the value of ``polymorphic_identity``
for the mapped class to the ``discriminator`` attribute,
thus persisting the value to the ``discriminator`` column
in the database.
.. warning::
Currently, **only one discriminator column may be set**, typically
on the base-most class in the hierarchy. "Cascading" polymorphic
columns are not yet supported.
.. seealso::
:ref:`inheritance_toplevel`
:param polymorphic_identity: Specifies the value which
identifies this particular class as returned by the column expression
referred to by the :paramref:`_orm.Mapper.polymorphic_on` setting. As
rows are received, the value corresponding to the
:paramref:`_orm.Mapper.polymorphic_on` column expression is compared
to this value, indicating which subclass should be used for the newly
reconstructed object.
.. seealso::
:ref:`inheritance_toplevel`
:param properties: A dictionary mapping the string names of object
attributes to :class:`.MapperProperty` instances, which define the
persistence behavior of that attribute. Note that
:class:`_schema.Column`
objects present in
the mapped :class:`_schema.Table` are automatically placed into
``ColumnProperty`` instances upon mapping, unless overridden.
When using Declarative, this argument is passed automatically,
based on all those :class:`.MapperProperty` instances declared
in the declared class body.
.. seealso::
:ref:`orm_mapping_properties` - in the
:ref:`orm_mapping_classes_toplevel`
:param primary_key: A list of :class:`_schema.Column`
objects, or alternatively string names of attribute names which
refer to :class:`_schema.Column`, which define
the primary key to be used against this mapper's selectable unit.
This is normally simply the primary key of the ``local_table``, but
can be overridden here.
.. versionchanged:: 2.0.2 :paramref:`_orm.Mapper.primary_key`
arguments may be indicated as string attribute names as well.
.. seealso::
:ref:`mapper_primary_key` - background and example use
:param version_id_col: A :class:`_schema.Column`
that will be used to keep a running version id of rows
in the table. This is used to detect concurrent updates or
the presence of stale data in a flush. The methodology is to
detect if an UPDATE statement does not match the last known
version id, a
:class:`~sqlalchemy.orm.exc.StaleDataError` exception is
thrown.
By default, the column must be of :class:`.Integer` type,
unless ``version_id_generator`` specifies an alternative version
generator.
.. seealso::
:ref:`mapper_version_counter` - discussion of version counting
and rationale.
:param version_id_generator: Define how new version ids should
be generated. Defaults to ``None``, which indicates that
a simple integer counting scheme be employed. To provide a custom
versioning scheme, provide a callable function of the form::
def generate_version(version):
return next_version
Alternatively, server-side versioning functions such as triggers,
or programmatic versioning schemes outside of the version id
generator may be used, by specifying the value ``False``.
Please see :ref:`server_side_version_counter` for a discussion
of important points when using this option.
.. seealso::
:ref:`custom_version_counter`
:ref:`server_side_version_counter`
:param with_polymorphic: A tuple in the form ``(<classes>,
<selectable>)`` indicating the default style of "polymorphic"
loading, that is, which tables are queried at once. <classes> is
any single or list of mappers and/or classes indicating the
inherited classes that should be loaded at once. The special value
``'*'`` may be used to indicate all descending classes should be
loaded immediately. The second tuple argument <selectable>
indicates a selectable that will be used to query for multiple
classes.
The :paramref:`_orm.Mapper.polymorphic_load` parameter may be
preferable over the use of :paramref:`_orm.Mapper.with_polymorphic`
in modern mappings to indicate a per-subclass technique of
indicating polymorphic loading styles.
.. seealso::
:ref:`with_polymorphic_mapper_config`
"""
self.class_ = util.assert_arg_type(class_, type, "class_")
self._sort_key = "%s.%s" % (
self.class_.__module__,
self.class_.__name__,
)
self._primary_key_argument = util.to_list(primary_key)
self.non_primary = non_primary
self.always_refresh = always_refresh
if isinstance(version_id_col, MapperProperty):
self.version_id_prop = version_id_col
self.version_id_col = None
else:
self.version_id_col = (
coercions.expect(
roles.ColumnArgumentOrKeyRole,
version_id_col,
argname="version_id_col",
)
if version_id_col is not None
else None
)
if version_id_generator is False:
self.version_id_generator = False
elif version_id_generator is None:
self.version_id_generator = lambda x: (x or 0) + 1
else:
self.version_id_generator = version_id_generator
self.concrete = concrete
self.single = False
if inherits is not None:
self.inherits = _parse_mapper_argument(inherits)
else:
self.inherits = None
if local_table is not None:
self.local_table = coercions.expect(
roles.StrictFromClauseRole,
local_table,
disable_inspection=True,
argname="local_table",
)
elif self.inherits:
# note this is a new flow as of 2.0 so that
# .local_table need not be Optional
self.local_table = self.inherits.local_table
self.single = True
else:
raise sa_exc.ArgumentError(
f"Mapper[{self.class_.__name__}(None)] has None for a "
"primary table argument and does not specify 'inherits'"
)
if inherit_condition is not None:
self.inherit_condition = coercions.expect(
roles.OnClauseRole, inherit_condition
)
else:
self.inherit_condition = None
self.inherit_foreign_keys = inherit_foreign_keys
self._init_properties = dict(properties) if properties else {}
self._delete_orphans = []
self.batch = batch
self.eager_defaults = eager_defaults
self.column_prefix = column_prefix
# interim - polymorphic_on is further refined in
# _configure_polymorphic_setter
self.polymorphic_on = (
coercions.expect( # type: ignore
roles.ColumnArgumentOrKeyRole,
polymorphic_on,
argname="polymorphic_on",
)
if polymorphic_on is not None
else None
)
self.polymorphic_abstract = polymorphic_abstract
self._dependency_processors = []
self.validators = util.EMPTY_DICT
self.passive_updates = passive_updates
self.passive_deletes = passive_deletes
self.legacy_is_orphan = legacy_is_orphan
self._clause_adapter = None
self._requires_row_aliasing = False
self._inherits_equated_pairs = None
self._memoized_values = {}
self._compiled_cache_size = _compiled_cache_size
self._reconstructor = None
self.allow_partial_pks = allow_partial_pks
if self.inherits and not self.concrete:
self.confirm_deleted_rows = False
else:
self.confirm_deleted_rows = confirm_deleted_rows
self._set_with_polymorphic(with_polymorphic)
self.polymorphic_load = polymorphic_load
# our 'polymorphic identity', a string name that when located in a
# result set row indicates this Mapper should be used to construct
# the object instance for that row.
self.polymorphic_identity = polymorphic_identity
# a dictionary of 'polymorphic identity' names, associating those
# names with Mappers that will be used to construct object instances
# upon a select operation.
if _polymorphic_map is None:
self.polymorphic_map = {}
else:
self.polymorphic_map = _polymorphic_map
if include_properties is not None:
self.include_properties = util.to_set(include_properties)
else:
self.include_properties = None
if exclude_properties:
self.exclude_properties = util.to_set(exclude_properties)
else:
self.exclude_properties = None
# prevent this mapper from being constructed
# while a configure_mappers() is occurring (and defer a
# configure_mappers() until construction succeeds)
with _CONFIGURE_MUTEX:
cast("MapperEvents", self.dispatch._events)._new_mapper_instance(
class_, self
)
self._configure_inheritance()
self._configure_class_instrumentation()
self._configure_properties()
self._configure_polymorphic_setter()
self._configure_pks()
self.registry._flag_new_mapper(self)
self._log("constructed")
self._expire_memoizations()
self.dispatch.after_mapper_constructed(self, self.class_)
def _prefer_eager_defaults(self, dialect, table):
if self.eager_defaults == "auto":
if not table.implicit_returning:
return False
return (
table in self._server_default_col_keys
and dialect.insert_executemany_returning
)
else:
return self.eager_defaults
def _gen_cache_key(self, anon_map, bindparams):
return (self,)
# ### BEGIN
# ATTRIBUTE DECLARATIONS START HERE
is_mapper = True
"""Part of the inspection API."""
represents_outer_join = False
registry: _RegistryType
@property
def mapper(self) -> Mapper[_O]:
"""Part of the inspection API.
Returns self.
"""
return self
@property
def entity(self):
r"""Part of the inspection API.
Returns self.class\_.
"""
return self.class_
class_: Type[_O]
"""The class to which this :class:`_orm.Mapper` is mapped."""
_identity_class: Type[_O]
_delete_orphans: List[Tuple[str, Type[Any]]]
_dependency_processors: List[DependencyProcessor]
_memoized_values: Dict[Any, Callable[[], Any]]
_inheriting_mappers: util.WeakSequence[Mapper[Any]]
_all_tables: Set[TableClause]
_polymorphic_attr_key: Optional[str]
_pks_by_table: Dict[FromClause, OrderedSet[ColumnClause[Any]]]
_cols_by_table: Dict[FromClause, OrderedSet[ColumnElement[Any]]]
_props: util.OrderedDict[str, MapperProperty[Any]]
_init_properties: Dict[str, MapperProperty[Any]]
_columntoproperty: _ColumnMapping
_set_polymorphic_identity: Optional[Callable[[InstanceState[_O]], None]]
_validate_polymorphic_identity: Optional[
Callable[[Mapper[_O], InstanceState[_O], _InstanceDict], None]
]
tables: Sequence[TableClause]
"""A sequence containing the collection of :class:`_schema.Table`
or :class:`_schema.TableClause` objects which this :class:`_orm.Mapper`
is aware of.
If the mapper is mapped to a :class:`_expression.Join`, or an
:class:`_expression.Alias`
representing a :class:`_expression.Select`, the individual
:class:`_schema.Table`
objects that comprise the full construct will be represented here.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
validators: util.immutabledict[str, Tuple[str, Dict[str, Any]]]
"""An immutable dictionary of attributes which have been decorated
using the :func:`_orm.validates` decorator.
The dictionary contains string attribute names as keys
mapped to the actual validation method.
"""
always_refresh: bool
allow_partial_pks: bool
version_id_col: Optional[ColumnElement[Any]]
with_polymorphic: Optional[
Tuple[
Union[Literal["*"], Sequence[Union[Mapper[Any], Type[Any]]]],
Optional[FromClause],
]
]
version_id_generator: Optional[Union[Literal[False], Callable[[Any], Any]]]
local_table: FromClause
"""The immediate :class:`_expression.FromClause` to which this
:class:`_orm.Mapper` refers.
Typically is an instance of :class:`_schema.Table`, may be any
:class:`.FromClause`.
The "local" table is the
selectable that the :class:`_orm.Mapper` is directly responsible for
managing from an attribute access and flush perspective. For
non-inheriting mappers, :attr:`.Mapper.local_table` will be the same
as :attr:`.Mapper.persist_selectable`. For inheriting mappers,
:attr:`.Mapper.local_table` refers to the specific portion of
:attr:`.Mapper.persist_selectable` that includes the columns to which
this :class:`.Mapper` is loading/persisting, such as a particular
:class:`.Table` within a join.
.. seealso::
:attr:`_orm.Mapper.persist_selectable`.
:attr:`_orm.Mapper.selectable`.
"""
persist_selectable: FromClause
"""The :class:`_expression.FromClause` to which this :class:`_orm.Mapper`
is mapped.
Typically is an instance of :class:`_schema.Table`, may be any
:class:`.FromClause`.
The :attr:`_orm.Mapper.persist_selectable` is similar to
:attr:`.Mapper.local_table`, but represents the :class:`.FromClause` that
represents the inheriting class hierarchy overall in an inheritance
scenario.
:attr.`.Mapper.persist_selectable` is also separate from the
:attr:`.Mapper.selectable` attribute, the latter of which may be an
alternate subquery used for selecting columns.
:attr.`.Mapper.persist_selectable` is oriented towards columns that
will be written on a persist operation.
.. seealso::
:attr:`_orm.Mapper.selectable`.
:attr:`_orm.Mapper.local_table`.
"""
inherits: Optional[Mapper[Any]]
"""References the :class:`_orm.Mapper` which this :class:`_orm.Mapper`
inherits from, if any.
"""
inherit_condition: Optional[ColumnElement[bool]]
configured: bool = False
"""Represent ``True`` if this :class:`_orm.Mapper` has been configured.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
.. seealso::
:func:`.configure_mappers`.
"""
concrete: bool
"""Represent ``True`` if this :class:`_orm.Mapper` is a concrete
inheritance mapper.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
primary_key: Tuple[Column[Any], ...]
"""An iterable containing the collection of :class:`_schema.Column`
objects
which comprise the 'primary key' of the mapped table, from the
perspective of this :class:`_orm.Mapper`.
This list is against the selectable in
:attr:`_orm.Mapper.persist_selectable`.
In the case of inheriting mappers, some columns may be managed by a
superclass mapper. For example, in the case of a
:class:`_expression.Join`, the
primary key is determined by all of the primary key columns across all
tables referenced by the :class:`_expression.Join`.
The list is also not necessarily the same as the primary key column
collection associated with the underlying tables; the :class:`_orm.Mapper`
features a ``primary_key`` argument that can override what the
:class:`_orm.Mapper` considers as primary key columns.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
class_manager: ClassManager[_O]
"""The :class:`.ClassManager` which maintains event listeners
and class-bound descriptors for this :class:`_orm.Mapper`.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
single: bool
"""Represent ``True`` if this :class:`_orm.Mapper` is a single table
inheritance mapper.
:attr:`_orm.Mapper.local_table` will be ``None`` if this flag is set.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
non_primary: bool
"""Represent ``True`` if this :class:`_orm.Mapper` is a "non-primary"
mapper, e.g. a mapper that is used only to select rows but not for
persistence management.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
polymorphic_on: Optional[KeyedColumnElement[Any]]
"""The :class:`_schema.Column` or SQL expression specified as the
``polymorphic_on`` argument
for this :class:`_orm.Mapper`, within an inheritance scenario.
This attribute is normally a :class:`_schema.Column` instance but
may also be an expression, such as one derived from
:func:`.cast`.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
polymorphic_map: Dict[Any, Mapper[Any]]
"""A mapping of "polymorphic identity" identifiers mapped to
:class:`_orm.Mapper` instances, within an inheritance scenario.
The identifiers can be of any type which is comparable to the
type of column represented by :attr:`_orm.Mapper.polymorphic_on`.
An inheritance chain of mappers will all reference the same
polymorphic map object. The object is used to correlate incoming
result rows to target mappers.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
polymorphic_identity: Optional[Any]
"""Represent an identifier which is matched against the
:attr:`_orm.Mapper.polymorphic_on` column during result row loading.
Used only with inheritance, this object can be of any type which is
comparable to the type of column represented by
:attr:`_orm.Mapper.polymorphic_on`.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
base_mapper: Mapper[Any]
"""The base-most :class:`_orm.Mapper` in an inheritance chain.
In a non-inheriting scenario, this attribute will always be this
:class:`_orm.Mapper`. In an inheritance scenario, it references
the :class:`_orm.Mapper` which is parent to all other :class:`_orm.Mapper`
objects in the inheritance chain.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
columns: ReadOnlyColumnCollection[str, Column[Any]]
"""A collection of :class:`_schema.Column` or other scalar expression
objects maintained by this :class:`_orm.Mapper`.
The collection behaves the same as that of the ``c`` attribute on
any :class:`_schema.Table` object,
except that only those columns included in
this mapping are present, and are keyed based on the attribute name
defined in the mapping, not necessarily the ``key`` attribute of the
:class:`_schema.Column` itself. Additionally, scalar expressions mapped
by :func:`.column_property` are also present here.
This is a *read only* attribute determined during mapper construction.
Behavior is undefined if directly modified.
"""
c: ReadOnlyColumnCollection[str, Column[Any]]
"""A synonym for :attr:`_orm.Mapper.columns`."""
@util.non_memoized_property
@util.deprecated("1.3", "Use .persist_selectable")
def mapped_table(self):
return self.persist_selectable
@util.memoized_property
def _path_registry(self) -> CachingEntityRegistry:
return PathRegistry.per_mapper(self)
def _configure_inheritance(self):
"""Configure settings related to inheriting and/or inherited mappers
being present."""
# a set of all mappers which inherit from this one.
self._inheriting_mappers = util.WeakSequence()
if self.inherits:
if not issubclass(self.class_, self.inherits.class_):
raise sa_exc.ArgumentError(
"Class '%s' does not inherit from '%s'"
% (self.class_.__name__, self.inherits.class_.__name__)
)
self.dispatch._update(self.inherits.dispatch)
if self.non_primary != self.inherits.non_primary:
np = not self.non_primary and "primary" or "non-primary"
raise sa_exc.ArgumentError(
"Inheritance of %s mapper for class '%s' is "
"only allowed from a %s mapper"
% (np, self.class_.__name__, np)
)
if self.single:
self.persist_selectable = self.inherits.persist_selectable
elif self.local_table is not self.inherits.local_table:
if self.concrete:
self.persist_selectable = self.local_table
for mapper in self.iterate_to_root():
if mapper.polymorphic_on is not None:
mapper._requires_row_aliasing = True
else:
if self.inherit_condition is None:
# figure out inherit condition from our table to the
# immediate table of the inherited mapper, not its
# full table which could pull in other stuff we don't
# want (allows test/inheritance.InheritTest4 to pass)
try:
self.inherit_condition = sql_util.join_condition(
self.inherits.local_table, self.local_table
)
except sa_exc.NoForeignKeysError as nfe:
assert self.inherits.local_table is not None
assert self.local_table is not None
raise sa_exc.NoForeignKeysError(
"Can't determine the inherit condition "
"between inherited table '%s' and "
"inheriting "
"table '%s'; tables have no "
"foreign key relationships established. "
"Please ensure the inheriting table has "
"a foreign key relationship to the "
"inherited "
"table, or provide an "
"'on clause' using "
"the 'inherit_condition' mapper argument."
% (
self.inherits.local_table.description,
self.local_table.description,
)
) from nfe
except sa_exc.AmbiguousForeignKeysError as afe:
assert self.inherits.local_table is not None
assert self.local_table is not None
raise sa_exc.AmbiguousForeignKeysError(
"Can't determine the inherit condition "
"between inherited table '%s' and "
"inheriting "
"table '%s'; tables have more than one "
"foreign key relationship established. "
"Please specify the 'on clause' using "
"the 'inherit_condition' mapper argument."
% (
self.inherits.local_table.description,
self.local_table.description,
)
) from afe
assert self.inherits.persist_selectable is not None
self.persist_selectable = sql.join(
self.inherits.persist_selectable,
self.local_table,
self.inherit_condition,
)
fks = util.to_set(self.inherit_foreign_keys)
self._inherits_equated_pairs = sql_util.criterion_as_pairs(
self.persist_selectable.onclause,
consider_as_foreign_keys=fks,
)
else:
self.persist_selectable = self.local_table
if self.polymorphic_identity is None:
self._identity_class = self.class_
if (
not self.polymorphic_abstract
and self.inherits.base_mapper.polymorphic_on is not None
):
util.warn(
f"{self} does not indicate a 'polymorphic_identity', "
"yet is part of an inheritance hierarchy that has a "
f"'polymorphic_on' column of "
f"'{self.inherits.base_mapper.polymorphic_on}'. "
"If this is an intermediary class that should not be "
"instantiated, the class may either be left unmapped, "
"or may include the 'polymorphic_abstract=True' "
"parameter in its Mapper arguments. To leave the "
"class unmapped when using Declarative, set the "
"'__abstract__ = True' attribute on the class."
)
elif self.concrete:
self._identity_class = self.class_
else:
self._identity_class = self.inherits._identity_class
if self.version_id_col is None:
self.version_id_col = self.inherits.version_id_col
self.version_id_generator = self.inherits.version_id_generator
elif (
self.inherits.version_id_col is not None
and self.version_id_col is not self.inherits.version_id_col
):
util.warn(
"Inheriting version_id_col '%s' does not match inherited "
"version_id_col '%s' and will not automatically populate "
"the inherited versioning column. "
"version_id_col should only be specified on "
"the base-most mapper that includes versioning."
% (
self.version_id_col.description,
self.inherits.version_id_col.description,
)
)
self.polymorphic_map = self.inherits.polymorphic_map
self.batch = self.inherits.batch
self.inherits._inheriting_mappers.append(self)
self.base_mapper = self.inherits.base_mapper
self.passive_updates = self.inherits.passive_updates
self.passive_deletes = (
self.inherits.passive_deletes or self.passive_deletes
)
self._all_tables = self.inherits._all_tables
if self.polymorphic_identity is not None:
if self.polymorphic_identity in self.polymorphic_map:
util.warn(
"Reassigning polymorphic association for identity %r "
"from %r to %r: Check for duplicate use of %r as "
"value for polymorphic_identity."
% (
self.polymorphic_identity,
self.polymorphic_map[self.polymorphic_identity],
self,
self.polymorphic_identity,
)
)
self.polymorphic_map[self.polymorphic_identity] = self
if self.polymorphic_load and self.concrete:
raise sa_exc.ArgumentError(
"polymorphic_load is not currently supported "
"with concrete table inheritance"
)
if self.polymorphic_load == "inline":
self.inherits._add_with_polymorphic_subclass(self)
elif self.polymorphic_load == "selectin":
pass
elif self.polymorphic_load is not None:
raise sa_exc.ArgumentError(
"unknown argument for polymorphic_load: %r"
% self.polymorphic_load
)
else:
self._all_tables = set()
self.base_mapper = self
assert self.local_table is not None
self.persist_selectable = self.local_table
if self.polymorphic_identity is not None:
self.polymorphic_map[self.polymorphic_identity] = self
self._identity_class = self.class_
if self.persist_selectable is None:
raise sa_exc.ArgumentError(
"Mapper '%s' does not have a persist_selectable specified."
% self
)
def _set_with_polymorphic(
self, with_polymorphic: Optional[_WithPolymorphicArg]
) -> None:
if with_polymorphic == "*":
self.with_polymorphic = ("*", None)
elif isinstance(with_polymorphic, (tuple, list)):
if isinstance(with_polymorphic[0], (str, tuple, list)):
self.with_polymorphic = cast(
"""Tuple[
Union[
Literal["*"],
Sequence[Union["Mapper[Any]", Type[Any]]],
],
Optional["FromClause"],
]""",
with_polymorphic,
)
else:
self.with_polymorphic = (with_polymorphic, None)
elif with_polymorphic is not None:
raise sa_exc.ArgumentError(
f"Invalid setting for with_polymorphic: {with_polymorphic!r}"
)
else:
self.with_polymorphic = None
if self.with_polymorphic and self.with_polymorphic[1] is not None:
self.with_polymorphic = (
self.with_polymorphic[0],
coercions.expect(
roles.StrictFromClauseRole,
self.with_polymorphic[1],
allow_select=True,
),
)
if self.configured:
self._expire_memoizations()
def _add_with_polymorphic_subclass(self, mapper):
subcl = mapper.class_
if self.with_polymorphic is None:
self._set_with_polymorphic((subcl,))
elif self.with_polymorphic[0] != "*":
assert isinstance(self.with_polymorphic[0], tuple)
self._set_with_polymorphic(
(self.with_polymorphic[0] + (subcl,), self.with_polymorphic[1])
)
def _set_concrete_base(self, mapper):
"""Set the given :class:`_orm.Mapper` as the 'inherits' for this
:class:`_orm.Mapper`, assuming this :class:`_orm.Mapper` is concrete
and does not already have an inherits."""
assert self.concrete
assert not self.inherits
assert isinstance(mapper, Mapper)
self.inherits = mapper
self.inherits.polymorphic_map.update(self.polymorphic_map)
self.polymorphic_map = self.inherits.polymorphic_map
for mapper in self.iterate_to_root():
if mapper.polymorphic_on is not None:
mapper._requires_row_aliasing = True
self.batch = self.inherits.batch
for mp in self.self_and_descendants:
mp.base_mapper = self.inherits.base_mapper
self.inherits._inheriting_mappers.append(self)
self.passive_updates = self.inherits.passive_updates
self._all_tables = self.inherits._all_tables
for key, prop in mapper._props.items():
if key not in self._props and not self._should_exclude(
key, key, local=False, column=None
):
self._adapt_inherited_property(key, prop, False)
def _set_polymorphic_on(self, polymorphic_on):
self.polymorphic_on = polymorphic_on
self._configure_polymorphic_setter(True)
def _configure_class_instrumentation(self):
"""If this mapper is to be a primary mapper (i.e. the
non_primary flag is not set), associate this Mapper with the
given class and entity name.
Subsequent calls to ``class_mapper()`` for the ``class_`` / ``entity``
name combination will return this mapper. Also decorate the
`__init__` method on the mapped class to include optional
auto-session attachment logic.
"""
# we expect that declarative has applied the class manager
# already and set up a registry. if this is None,
# this raises as of 2.0.
manager = attributes.opt_manager_of_class(self.class_)
if self.non_primary:
if not manager or not manager.is_mapped:
raise sa_exc.InvalidRequestError(
"Class %s has no primary mapper configured. Configure "
"a primary mapper first before setting up a non primary "
"Mapper." % self.class_
)
self.class_manager = manager
assert manager.registry is not None
self.registry = manager.registry
self._identity_class = manager.mapper._identity_class
manager.registry._add_non_primary_mapper(self)
return
if manager is None or not manager.registry:
raise sa_exc.InvalidRequestError(
"The _mapper() function and Mapper() constructor may not be "
"invoked directly outside of a declarative registry."
" Please use the sqlalchemy.orm.registry.map_imperatively() "
"function for a classical mapping."
)
self.dispatch.instrument_class(self, self.class_)
# this invokes the class_instrument event and sets up
# the __init__ method. documented behavior is that this must
# occur after the instrument_class event above.
# yes two events with the same two words reversed and different APIs.
# :(
manager = instrumentation.register_class(
self.class_,
mapper=self,
expired_attribute_loader=util.partial(
loading.load_scalar_attributes, self
),
# finalize flag means instrument the __init__ method
# and call the class_instrument event
finalize=True,
)
self.class_manager = manager
assert manager.registry is not None
self.registry = manager.registry
# The remaining members can be added by any mapper,
# e_name None or not.
if manager.mapper is None:
return
event.listen(manager, "init", _event_on_init, raw=True)
for key, method in util.iterate_attributes(self.class_):
if key == "__init__" and hasattr(method, "_sa_original_init"):
method = method._sa_original_init
if hasattr(method, "__func__"):
method = method.__func__
if callable(method):
if hasattr(method, "__sa_reconstructor__"):
self._reconstructor = method
event.listen(manager, "load", _event_on_load, raw=True)
elif hasattr(method, "__sa_validators__"):
validation_opts = method.__sa_validation_opts__
for name in method.__sa_validators__:
if name in self.validators:
raise sa_exc.InvalidRequestError(
"A validation function for mapped "
"attribute %r on mapper %s already exists."
% (name, self)
)
self.validators = self.validators.union(
{name: (method, validation_opts)}
)
def _set_dispose_flags(self) -> None:
self.configured = True
self._ready_for_configure = True
self._dispose_called = True
self.__dict__.pop("_configure_failed", None)
def _str_arg_to_mapped_col(self, argname: str, key: str) -> Column[Any]:
try:
prop = self._props[key]
except KeyError as err:
raise sa_exc.ArgumentError(
f"Can't determine {argname} column '{key}' - "
"no attribute is mapped to this name."
) from err
try:
expr = prop.expression
except AttributeError as ae:
raise sa_exc.ArgumentError(
f"Can't determine {argname} column '{key}'; "
"property does not refer to a single mapped Column"
) from ae
if not isinstance(expr, Column):
raise sa_exc.ArgumentError(
f"Can't determine {argname} column '{key}'; "
"property does not refer to a single "
"mapped Column"
)
return expr
def _configure_pks(self) -> None:
self.tables = sql_util.find_tables(self.persist_selectable)
self._all_tables.update(t for t in self.tables)
self._pks_by_table = {}
self._cols_by_table = {}
all_cols = util.column_set(
chain(*[col.proxy_set for col in self._columntoproperty])
)
pk_cols = util.column_set(c for c in all_cols if c.primary_key)
# identify primary key columns which are also mapped by this mapper.
for fc in set(self.tables).union([self.persist_selectable]):
if fc.primary_key and pk_cols.issuperset(fc.primary_key):
# ordering is important since it determines the ordering of
# mapper.primary_key (and therefore query.get())
self._pks_by_table[fc] = util.ordered_column_set( # type: ignore # noqa: E501
fc.primary_key
).intersection(
pk_cols
)
self._cols_by_table[fc] = util.ordered_column_set(fc.c).intersection( # type: ignore # noqa: E501
all_cols
)
if self._primary_key_argument:
coerced_pk_arg = [
(
self._str_arg_to_mapped_col("primary_key", c)
if isinstance(c, str)
else c
)
for c in (
coercions.expect(
roles.DDLConstraintColumnRole,
coerce_pk,
argname="primary_key",
)
for coerce_pk in self._primary_key_argument
)
]
else:
coerced_pk_arg = None
# if explicit PK argument sent, add those columns to the
# primary key mappings
if coerced_pk_arg:
for k in coerced_pk_arg:
if k.table not in self._pks_by_table:
self._pks_by_table[k.table] = util.OrderedSet()
self._pks_by_table[k.table].add(k)
# otherwise, see that we got a full PK for the mapped table
elif (
self.persist_selectable not in self._pks_by_table
or len(self._pks_by_table[self.persist_selectable]) == 0
):
raise sa_exc.ArgumentError(
"Mapper %s could not assemble any primary "
"key columns for mapped table '%s'"
% (self, self.persist_selectable.description)
)
elif self.local_table not in self._pks_by_table and isinstance(
self.local_table, schema.Table
):
util.warn(
"Could not assemble any primary "
"keys for locally mapped table '%s' - "
"no rows will be persisted in this Table."
% self.local_table.description
)
if (
self.inherits
and not self.concrete
and not self._primary_key_argument
):
# if inheriting, the "primary key" for this mapper is
# that of the inheriting (unless concrete or explicit)
self.primary_key = self.inherits.primary_key
else:
# determine primary key from argument or persist_selectable pks
primary_key: Collection[ColumnElement[Any]]
if coerced_pk_arg:
primary_key = [
cc if cc is not None else c
for cc, c in (
(self.persist_selectable.corresponding_column(c), c)
for c in coerced_pk_arg
)
]
else:
# if heuristically determined PKs, reduce to the minimal set
# of columns by eliminating FK->PK pairs for a multi-table
# expression. May over-reduce for some kinds of UNIONs
# / CTEs; use explicit PK argument for these special cases
primary_key = sql_util.reduce_columns(
self._pks_by_table[self.persist_selectable],
ignore_nonexistent_tables=True,
)
if len(primary_key) == 0:
raise sa_exc.ArgumentError(
"Mapper %s could not assemble any primary "
"key columns for mapped table '%s'"
% (self, self.persist_selectable.description)
)
self.primary_key = tuple(primary_key)
self._log("Identified primary key columns: %s", primary_key)
# determine cols that aren't expressed within our tables; mark these
# as "read only" properties which are refreshed upon INSERT/UPDATE
self._readonly_props = {
self._columntoproperty[col]
for col in self._columntoproperty
if self._columntoproperty[col] not in self._identity_key_props
and (
not hasattr(col, "table")
or col.table not in self._cols_by_table
)
}
def _configure_properties(self) -> None:
self.columns = self.c = sql_base.ColumnCollection() # type: ignore
# object attribute names mapped to MapperProperty objects
self._props = util.OrderedDict()
# table columns mapped to MapperProperty
self._columntoproperty = _ColumnMapping(self)
explicit_col_props_by_column: Dict[
KeyedColumnElement[Any], Tuple[str, ColumnProperty[Any]]
] = {}
explicit_col_props_by_key: Dict[str, ColumnProperty[Any]] = {}
# step 1: go through properties that were explicitly passed
# in the properties dictionary. For Columns that are local, put them
# aside in a separate collection we will reconcile with the Table
# that's given. For other properties, set them up in _props now.
if self._init_properties:
for key, prop_arg in self._init_properties.items():
if not isinstance(prop_arg, MapperProperty):
possible_col_prop = self._make_prop_from_column(
key, prop_arg
)
else:
possible_col_prop = prop_arg
# issue #8705. if the explicit property is actually a
# Column that is local to the local Table, don't set it up
# in ._props yet, integrate it into the order given within
# the Table.
_map_as_property_now = True
if isinstance(possible_col_prop, properties.ColumnProperty):
for given_col in possible_col_prop.columns:
if self.local_table.c.contains_column(given_col):
_map_as_property_now = False
explicit_col_props_by_key[key] = possible_col_prop
explicit_col_props_by_column[given_col] = (
key,
possible_col_prop,
)
if _map_as_property_now:
self._configure_property(
key,
possible_col_prop,
init=False,
)
# step 2: pull properties from the inherited mapper. reconcile
# columns with those which are explicit above. for properties that
# are only in the inheriting mapper, set them up as local props
if self.inherits:
for key, inherited_prop in self.inherits._props.items():
if self._should_exclude(key, key, local=False, column=None):
continue
incoming_prop = explicit_col_props_by_key.get(key)
if incoming_prop:
new_prop = self._reconcile_prop_with_incoming_columns(
key,
inherited_prop,
warn_only=False,
incoming_prop=incoming_prop,
)
explicit_col_props_by_key[key] = new_prop
for inc_col in incoming_prop.columns:
explicit_col_props_by_column[inc_col] = (
key,
new_prop,
)
elif key not in self._props:
self._adapt_inherited_property(key, inherited_prop, False)
# step 3. Iterate through all columns in the persist selectable.
# this includes not only columns in the local table / fromclause,
# but also those columns in the superclass table if we are joined
# inh or single inh mapper. map these columns as well. additional
# reconciliation against inherited columns occurs here also.
for column in self.persist_selectable.columns:
if column in explicit_col_props_by_column:
# column was explicitly passed to properties; configure
# it now in the order in which it corresponds to the
# Table / selectable
key, prop = explicit_col_props_by_column[column]
self._configure_property(key, prop, init=False)
continue
elif column in self._columntoproperty:
continue
column_key = (self.column_prefix or "") + column.key
if self._should_exclude(
column.key,
column_key,
local=self.local_table.c.contains_column(column),
column=column,
):
continue
# adjust the "key" used for this column to that
# of the inheriting mapper
for mapper in self.iterate_to_root():
if column in mapper._columntoproperty:
column_key = mapper._columntoproperty[column].key
self._configure_property(
column_key,
column,
init=False,
setparent=True,
)
def _configure_polymorphic_setter(self, init=False):
"""Configure an attribute on the mapper representing the
'polymorphic_on' column, if applicable, and not
already generated by _configure_properties (which is typical).
Also create a setter function which will assign this
attribute to the value of the 'polymorphic_identity'
upon instance construction, also if applicable. This
routine will run when an instance is created.
"""
setter = False
polymorphic_key: Optional[str] = None
if self.polymorphic_on is not None:
setter = True
if isinstance(self.polymorphic_on, str):
# polymorphic_on specified as a string - link
# it to mapped ColumnProperty
try:
self.polymorphic_on = self._props[self.polymorphic_on]
except KeyError as err:
raise sa_exc.ArgumentError(
"Can't determine polymorphic_on "
"value '%s' - no attribute is "
"mapped to this name." % self.polymorphic_on
) from err
if self.polymorphic_on in self._columntoproperty:
# polymorphic_on is a column that is already mapped
# to a ColumnProperty
prop = self._columntoproperty[self.polymorphic_on]
elif isinstance(self.polymorphic_on, MapperProperty):
# polymorphic_on is directly a MapperProperty,
# ensure it's a ColumnProperty
if not isinstance(
self.polymorphic_on, properties.ColumnProperty
):
raise sa_exc.ArgumentError(
"Only direct column-mapped "
"property or SQL expression "
"can be passed for polymorphic_on"
)
prop = self.polymorphic_on
else:
# polymorphic_on is a Column or SQL expression and
# doesn't appear to be mapped. this means it can be 1.
# only present in the with_polymorphic selectable or
# 2. a totally standalone SQL expression which we'd
# hope is compatible with this mapper's persist_selectable
col = self.persist_selectable.corresponding_column(
self.polymorphic_on
)
if col is None:
# polymorphic_on doesn't derive from any
# column/expression isn't present in the mapped
# table. we will make a "hidden" ColumnProperty
# for it. Just check that if it's directly a
# schema.Column and we have with_polymorphic, it's
# likely a user error if the schema.Column isn't
# represented somehow in either persist_selectable or
# with_polymorphic. Otherwise as of 0.7.4 we
# just go with it and assume the user wants it
# that way (i.e. a CASE statement)
setter = False
instrument = False
col = self.polymorphic_on
if isinstance(col, schema.Column) and (
self.with_polymorphic is None
or self.with_polymorphic[1] is None
or self.with_polymorphic[1].corresponding_column(col)
is None
):
raise sa_exc.InvalidRequestError(
"Could not map polymorphic_on column "
"'%s' to the mapped table - polymorphic "
"loads will not function properly"
% col.description
)
else:
# column/expression that polymorphic_on derives from
# is present in our mapped table
# and is probably mapped, but polymorphic_on itself
# is not. This happens when
# the polymorphic_on is only directly present in the
# with_polymorphic selectable, as when use
# polymorphic_union.
# we'll make a separate ColumnProperty for it.
instrument = True
key = getattr(col, "key", None)
if key:
if self._should_exclude(key, key, False, col):
raise sa_exc.InvalidRequestError(
"Cannot exclude or override the "
"discriminator column %r" % key
)
else:
self.polymorphic_on = col = col.label("_sa_polymorphic_on")
key = col.key
prop = properties.ColumnProperty(col, _instrument=instrument)
self._configure_property(key, prop, init=init, setparent=True)
# the actual polymorphic_on should be the first public-facing
# column in the property
self.polymorphic_on = prop.columns[0]
polymorphic_key = prop.key
else:
# no polymorphic_on was set.
# check inheriting mappers for one.
for mapper in self.iterate_to_root():
# determine if polymorphic_on of the parent
# should be propagated here. If the col
# is present in our mapped table, or if our mapped
# table is the same as the parent (i.e. single table
# inheritance), we can use it
if mapper.polymorphic_on is not None:
if self.persist_selectable is mapper.persist_selectable:
self.polymorphic_on = mapper.polymorphic_on
else:
self.polymorphic_on = (
self.persist_selectable
).corresponding_column(mapper.polymorphic_on)
# we can use the parent mapper's _set_polymorphic_identity
# directly; it ensures the polymorphic_identity of the
# instance's mapper is used so is portable to subclasses.
if self.polymorphic_on is not None:
self._set_polymorphic_identity = (
mapper._set_polymorphic_identity
)
self._polymorphic_attr_key = (
mapper._polymorphic_attr_key
)
self._validate_polymorphic_identity = (
mapper._validate_polymorphic_identity
)
else:
self._set_polymorphic_identity = None
self._polymorphic_attr_key = None
return
if self.polymorphic_abstract and self.polymorphic_on is None:
raise sa_exc.InvalidRequestError(
"The Mapper.polymorphic_abstract parameter may only be used "
"on a mapper hierarchy which includes the "
"Mapper.polymorphic_on parameter at the base of the hierarchy."
)
if setter:
def _set_polymorphic_identity(state):
dict_ = state.dict
# TODO: what happens if polymorphic_on column attribute name
# does not match .key?
polymorphic_identity = (
state.manager.mapper.polymorphic_identity
)
if (
polymorphic_identity is None
and state.manager.mapper.polymorphic_abstract
):
raise sa_exc.InvalidRequestError(
f"Can't instantiate class for {state.manager.mapper}; "
"mapper is marked polymorphic_abstract=True"
)
state.get_impl(polymorphic_key).set(
state,
dict_,
polymorphic_identity,
None,
)
self._polymorphic_attr_key = polymorphic_key
def _validate_polymorphic_identity(mapper, state, dict_):
if (
polymorphic_key in dict_
and dict_[polymorphic_key]
not in mapper._acceptable_polymorphic_identities
):
util.warn_limited(
"Flushing object %s with "
"incompatible polymorphic identity %r; the "
"object may not refresh and/or load correctly",
(state_str(state), dict_[polymorphic_key]),
)
self._set_polymorphic_identity = _set_polymorphic_identity
self._validate_polymorphic_identity = (
_validate_polymorphic_identity
)
else:
self._polymorphic_attr_key = None
self._set_polymorphic_identity = None
_validate_polymorphic_identity = None
@HasMemoized.memoized_attribute
def _version_id_prop(self):
if self.version_id_col is not None:
return self._columntoproperty[self.version_id_col]
else:
return None
@HasMemoized.memoized_attribute
def _acceptable_polymorphic_identities(self):
identities = set()
stack = deque([self])
while stack:
item = stack.popleft()
if item.persist_selectable is self.persist_selectable:
identities.add(item.polymorphic_identity)
stack.extend(item._inheriting_mappers)
return identities
@HasMemoized.memoized_attribute
def _prop_set(self):
return frozenset(self._props.values())
@util.preload_module("sqlalchemy.orm.descriptor_props")
def _adapt_inherited_property(self, key, prop, init):
descriptor_props = util.preloaded.orm_descriptor_props
if not self.concrete:
self._configure_property(key, prop, init=False, setparent=False)
elif key not in self._props:
# determine if the class implements this attribute; if not,
# or if it is implemented by the attribute that is handling the
# given superclass-mapped property, then we need to report that we
# can't use this at the instance level since we are a concrete
# mapper and we don't map this. don't trip user-defined
# descriptors that might have side effects when invoked.
implementing_attribute = self.class_manager._get_class_attr_mro(
key, prop
)
if implementing_attribute is prop or (
isinstance(
implementing_attribute, attributes.InstrumentedAttribute
)
and implementing_attribute._parententity is prop.parent
):
self._configure_property(
key,
descriptor_props.ConcreteInheritedProperty(),
init=init,
setparent=True,
)
@util.preload_module("sqlalchemy.orm.descriptor_props")
def _configure_property(
self,
key: str,
prop_arg: Union[KeyedColumnElement[Any], MapperProperty[Any]],
*,
init: bool = True,
setparent: bool = True,
warn_for_existing: bool = False,
) -> MapperProperty[Any]:
descriptor_props = util.preloaded.orm_descriptor_props
self._log(
"_configure_property(%s, %s)", key, prop_arg.__class__.__name__
)
if not isinstance(prop_arg, MapperProperty):
prop: MapperProperty[Any] = self._property_from_column(
key, prop_arg
)
else:
prop = prop_arg
if isinstance(prop, properties.ColumnProperty):
col = self.persist_selectable.corresponding_column(prop.columns[0])
# if the column is not present in the mapped table,
# test if a column has been added after the fact to the
# parent table (or their parent, etc.) [ticket:1570]
if col is None and self.inherits:
path = [self]
for m in self.inherits.iterate_to_root():
col = m.local_table.corresponding_column(prop.columns[0])
if col is not None:
for m2 in path:
m2.persist_selectable._refresh_for_new_column(col)
col = self.persist_selectable.corresponding_column(
prop.columns[0]
)
break
path.append(m)
# subquery expression, column not present in the mapped
# selectable.
if col is None:
col = prop.columns[0]
# column is coming in after _readonly_props was
# initialized; check for 'readonly'
if hasattr(self, "_readonly_props") and (
not hasattr(col, "table")
or col.table not in self._cols_by_table
):
self._readonly_props.add(prop)
else:
# if column is coming in after _cols_by_table was
# initialized, ensure the col is in the right set
if (
hasattr(self, "_cols_by_table")
and col.table in self._cols_by_table
and col not in self._cols_by_table[col.table]
):
self._cols_by_table[col.table].add(col)
# if this properties.ColumnProperty represents the "polymorphic
# discriminator" column, mark it. We'll need this when rendering
# columns in SELECT statements.
if not hasattr(prop, "_is_polymorphic_discriminator"):
prop._is_polymorphic_discriminator = (
col is self.polymorphic_on
or prop.columns[0] is self.polymorphic_on
)
if isinstance(col, expression.Label):
# new in 1.4, get column property against expressions
# to be addressable in subqueries
col.key = col._tq_key_label = key
self.columns.add(col, key)
for col in prop.columns:
for proxy_col in col.proxy_set:
self._columntoproperty[proxy_col] = prop
if getattr(prop, "key", key) != key:
util.warn(
f"ORM mapped property {self.class_.__name__}.{prop.key} being "
"assigned to attribute "
f"{key!r} is already associated with "
f"attribute {prop.key!r}. The attribute will be de-associated "
f"from {prop.key!r}."
)
prop.key = key
if setparent:
prop.set_parent(self, init)
if key in self._props and getattr(
self._props[key], "_mapped_by_synonym", False
):
syn = self._props[key]._mapped_by_synonym
raise sa_exc.ArgumentError(
"Can't call map_column=True for synonym %r=%r, "
"a ColumnProperty already exists keyed to the name "
"%r for column %r" % (syn, key, key, syn)
)
# replacement cases
# case one: prop is replacing a prop that we have mapped. this is
# independent of whatever might be in the actual class dictionary
if (
key in self._props
and not isinstance(
self._props[key], descriptor_props.ConcreteInheritedProperty
)
and not isinstance(prop, descriptor_props.SynonymProperty)
):
if warn_for_existing:
util.warn_deprecated(
f"User-placed attribute {self.class_.__name__}.{key} on "
f"{self} is replacing an existing ORM-mapped attribute. "
"Behavior is not fully defined in this case. This "
"use is deprecated and will raise an error in a future "
"release",
"2.0",
)
oldprop = self._props[key]
self._path_registry.pop(oldprop, None)
# case two: prop is replacing an attribute on the class of some kind.
# we have to be more careful here since it's normal when using
# Declarative that all the "declared attributes" on the class
# get replaced.
elif (
warn_for_existing
and self.class_.__dict__.get(key, None) is not None
and not isinstance(prop, descriptor_props.SynonymProperty)
and not isinstance(
self._props.get(key, None),
descriptor_props.ConcreteInheritedProperty,
)
):
util.warn_deprecated(
f"User-placed attribute {self.class_.__name__}.{key} on "
f"{self} is replacing an existing class-bound "
"attribute of the same name. "
"Behavior is not fully defined in this case. This "
"use is deprecated and will raise an error in a future "
"release",
"2.0",
)
self._props[key] = prop
if not self.non_primary:
prop.instrument_class(self)
for mapper in self._inheriting_mappers:
mapper._adapt_inherited_property(key, prop, init)
if init:
prop.init()
prop.post_instrument_class(self)
if self.configured:
self._expire_memoizations()
return prop
def _make_prop_from_column(
self,
key: str,
column: Union[
Sequence[KeyedColumnElement[Any]], KeyedColumnElement[Any]
],
) -> ColumnProperty[Any]:
columns = util.to_list(column)
mapped_column = []
for c in columns:
mc = self.persist_selectable.corresponding_column(c)
if mc is None:
mc = self.local_table.corresponding_column(c)
if mc is not None:
# if the column is in the local table but not the
# mapped table, this corresponds to adding a
# column after the fact to the local table.
# [ticket:1523]
self.persist_selectable._refresh_for_new_column(mc)
mc = self.persist_selectable.corresponding_column(c)
if mc is None:
raise sa_exc.ArgumentError(
"When configuring property '%s' on %s, "
"column '%s' is not represented in the mapper's "
"table. Use the `column_property()` function to "
"force this column to be mapped as a read-only "
"attribute." % (key, self, c)
)
mapped_column.append(mc)
return properties.ColumnProperty(*mapped_column)
def _reconcile_prop_with_incoming_columns(
self,
key: str,
existing_prop: MapperProperty[Any],
warn_only: bool,
incoming_prop: Optional[ColumnProperty[Any]] = None,
single_column: Optional[KeyedColumnElement[Any]] = None,
) -> ColumnProperty[Any]:
if incoming_prop and (
self.concrete
or not isinstance(existing_prop, properties.ColumnProperty)
):
return incoming_prop
existing_column = existing_prop.columns[0]
if incoming_prop and existing_column in incoming_prop.columns:
return incoming_prop
if incoming_prop is None:
assert single_column is not None
incoming_column = single_column
equated_pair_key = (existing_prop.columns[0], incoming_column)
else:
assert single_column is None
incoming_column = incoming_prop.columns[0]
equated_pair_key = (incoming_column, existing_prop.columns[0])
if (
(
not self._inherits_equated_pairs
or (equated_pair_key not in self._inherits_equated_pairs)
)
and not existing_column.shares_lineage(incoming_column)
and existing_column is not self.version_id_col
and incoming_column is not self.version_id_col
):
msg = (
"Implicitly combining column %s with column "
"%s under attribute '%s'. Please configure one "
"or more attributes for these same-named columns "
"explicitly."
% (
existing_prop.columns[-1],
incoming_column,
key,
)
)
if warn_only:
util.warn(msg)
else:
raise sa_exc.InvalidRequestError(msg)
# existing properties.ColumnProperty from an inheriting
# mapper. make a copy and append our column to it
# breakpoint()
new_prop = existing_prop.copy()
new_prop.columns.insert(0, incoming_column)
self._log(
"inserting column to existing list "
"in properties.ColumnProperty %s",
key,
)
return new_prop # type: ignore
@util.preload_module("sqlalchemy.orm.descriptor_props")
def _property_from_column(
self,
key: str,
column: KeyedColumnElement[Any],
) -> ColumnProperty[Any]:
"""generate/update a :class:`.ColumnProperty` given a
:class:`_schema.Column` or other SQL expression object."""
descriptor_props = util.preloaded.orm_descriptor_props
prop = self._props.get(key)
if isinstance(prop, properties.ColumnProperty):
return self._reconcile_prop_with_incoming_columns(
key,
prop,
single_column=column,
warn_only=prop.parent is not self,
)
elif prop is None or isinstance(
prop, descriptor_props.ConcreteInheritedProperty
):
return self._make_prop_from_column(key, column)
else:
raise sa_exc.ArgumentError(
"WARNING: when configuring property '%s' on %s, "
"column '%s' conflicts with property '%r'. "
"To resolve this, map the column to the class under a "
"different name in the 'properties' dictionary. Or, "
"to remove all awareness of the column entirely "
"(including its availability as a foreign key), "
"use the 'include_properties' or 'exclude_properties' "
"mapper arguments to control specifically which table "
"columns get mapped." % (key, self, column.key, prop)
)
@util.langhelpers.tag_method_for_warnings(
"This warning originated from the `configure_mappers()` process, "
"which was invoked automatically in response to a user-initiated "
"operation.",
sa_exc.SAWarning,
)
def _check_configure(self) -> None:
if self.registry._new_mappers:
_configure_registries({self.registry}, cascade=True)
def _post_configure_properties(self) -> None:
"""Call the ``init()`` method on all ``MapperProperties``
attached to this mapper.
This is a deferred configuration step which is intended
to execute once all mappers have been constructed.
"""
self._log("_post_configure_properties() started")
l = [(key, prop) for key, prop in self._props.items()]
for key, prop in l:
self._log("initialize prop %s", key)
if prop.parent is self and not prop._configure_started:
prop.init()
if prop._configure_finished:
prop.post_instrument_class(self)
self._log("_post_configure_properties() complete")
self.configured = True
def add_properties(self, dict_of_properties):
"""Add the given dictionary of properties to this mapper,
using `add_property`.
"""
for key, value in dict_of_properties.items():
self.add_property(key, value)
def add_property(
self, key: str, prop: Union[Column[Any], MapperProperty[Any]]
) -> None:
"""Add an individual MapperProperty to this mapper.
If the mapper has not been configured yet, just adds the
property to the initial properties dictionary sent to the
constructor. If this Mapper has already been configured, then
the given MapperProperty is configured immediately.
"""
prop = self._configure_property(
key, prop, init=self.configured, warn_for_existing=True
)
assert isinstance(prop, MapperProperty)
self._init_properties[key] = prop
def _expire_memoizations(self) -> None:
for mapper in self.iterate_to_root():
mapper._reset_memoizations()
@property
def _log_desc(self) -> str:
return (
"("
+ self.class_.__name__
+ "|"
+ (
self.local_table is not None
and self.local_table.description
or str(self.local_table)
)
+ (self.non_primary and "|non-primary" or "")
+ ")"
)
def _log(self, msg: str, *args: Any) -> None:
self.logger.info("%s " + msg, *((self._log_desc,) + args))
def _log_debug(self, msg: str, *args: Any) -> None:
self.logger.debug("%s " + msg, *((self._log_desc,) + args))
def __repr__(self) -> str:
return "<Mapper at 0x%x; %s>" % (id(self), self.class_.__name__)
def __str__(self) -> str:
return "Mapper[%s%s(%s)]" % (
self.class_.__name__,
self.non_primary and " (non-primary)" or "",
(
self.local_table.description
if self.local_table is not None
else self.persist_selectable.description
),
)
def _is_orphan(self, state: InstanceState[_O]) -> bool:
orphan_possible = False
for mapper in self.iterate_to_root():
for key, cls in mapper._delete_orphans:
orphan_possible = True
has_parent = attributes.manager_of_class(cls).has_parent(
state, key, optimistic=state.has_identity
)
if self.legacy_is_orphan and has_parent:
return False
elif not self.legacy_is_orphan and not has_parent:
return True
if self.legacy_is_orphan:
return orphan_possible
else:
return False
def has_property(self, key: str) -> bool:
return key in self._props
def get_property(
self, key: str, _configure_mappers: bool = False
) -> MapperProperty[Any]:
"""return a MapperProperty associated with the given key."""
if _configure_mappers:
self._check_configure()
try:
return self._props[key]
except KeyError as err:
raise sa_exc.InvalidRequestError(
f"Mapper '{self}' has no property '{key}'. If this property "
"was indicated from other mappers or configure events, ensure "
"registry.configure() has been called."
) from err
def get_property_by_column(
self, column: ColumnElement[_T]
) -> MapperProperty[_T]:
"""Given a :class:`_schema.Column` object, return the
:class:`.MapperProperty` which maps this column."""
return self._columntoproperty[column]
@property
def iterate_properties(self):
"""return an iterator of all MapperProperty objects."""
return iter(self._props.values())
def _mappers_from_spec(
self, spec: Any, selectable: Optional[FromClause]
) -> Sequence[Mapper[Any]]:
"""given a with_polymorphic() argument, return the set of mappers it
represents.
Trims the list of mappers to just those represented within the given
selectable, if present. This helps some more legacy-ish mappings.
"""
if spec == "*":
mappers = list(self.self_and_descendants)
elif spec:
mapper_set = set()
for m in util.to_list(spec):
m = _class_to_mapper(m)
if not m.isa(self):
raise sa_exc.InvalidRequestError(
"%r does not inherit from %r" % (m, self)
)
if selectable is None:
mapper_set.update(m.iterate_to_root())
else:
mapper_set.add(m)
mappers = [m for m in self.self_and_descendants if m in mapper_set]
else:
mappers = []
if selectable is not None:
tables = set(
sql_util.find_tables(selectable, include_aliases=True)
)
mappers = [m for m in mappers if m.local_table in tables]
return mappers
def _selectable_from_mappers(
self, mappers: Iterable[Mapper[Any]], innerjoin: bool
) -> FromClause:
"""given a list of mappers (assumed to be within this mapper's
inheritance hierarchy), construct an outerjoin amongst those mapper's
mapped tables.
"""
from_obj = self.persist_selectable
for m in mappers:
if m is self:
continue
if m.concrete:
raise sa_exc.InvalidRequestError(
"'with_polymorphic()' requires 'selectable' argument "
"when concrete-inheriting mappers are used."
)
elif not m.single:
if innerjoin:
from_obj = from_obj.join(
m.local_table, m.inherit_condition
)
else:
from_obj = from_obj.outerjoin(
m.local_table, m.inherit_condition
)
return from_obj
@HasMemoized.memoized_attribute
def _version_id_has_server_side_value(self) -> bool:
vid_col = self.version_id_col
if vid_col is None:
return False
elif not isinstance(vid_col, Column):
return True
else:
return vid_col.server_default is not None or (
vid_col.default is not None
and (
not vid_col.default.is_scalar
and not vid_col.default.is_callable
)
)
@HasMemoized.memoized_attribute
def _single_table_criterion(self):
if self.single and self.inherits and self.polymorphic_on is not None:
return self.polymorphic_on._annotate(
{"parententity": self, "parentmapper": self}
).in_(
[
m.polymorphic_identity
for m in self.self_and_descendants
if not m.polymorphic_abstract
]
)
else:
return None
@HasMemoized.memoized_attribute
def _has_aliased_polymorphic_fromclause(self):
"""return True if with_polymorphic[1] is an aliased fromclause,
like a subquery.
As of #8168, polymorphic adaption with ORMAdapter is used only
if this is present.
"""
return self.with_polymorphic and isinstance(
self.with_polymorphic[1],
expression.AliasedReturnsRows,
)
@HasMemoized.memoized_attribute
def _should_select_with_poly_adapter(self):
"""determine if _MapperEntity or _ORMColumnEntity will need to use
polymorphic adaption when setting up a SELECT as well as fetching
rows for mapped classes and subclasses against this Mapper.
moved here from context.py for #8456 to generalize the ruleset
for this condition.
"""
# this has been simplified as of #8456.
# rule is: if we have a with_polymorphic or a concrete-style
# polymorphic selectable, *or* if the base mapper has either of those,
# we turn on the adaption thing. if not, we do *no* adaption.
#
# (UPDATE for #8168: the above comment was not accurate, as we were
# still saying "do polymorphic" if we were using an auto-generated
# flattened JOIN for with_polymorphic.)
#
# this splits the behavior among the "regular" joined inheritance
# and single inheritance mappers, vs. the "weird / difficult"
# concrete and joined inh mappings that use a with_polymorphic of
# some kind or polymorphic_union.
#
# note we have some tests in test_polymorphic_rel that query against
# a subclass, then refer to the superclass that has a with_polymorphic
# on it (such as test_join_from_polymorphic_explicit_aliased_three).
# these tests actually adapt the polymorphic selectable (like, the
# UNION or the SELECT subquery with JOIN in it) to be just the simple
# subclass table. Hence even if we are a "plain" inheriting mapper
# but our base has a wpoly on it, we turn on adaption. This is a
# legacy case we should probably disable.
#
#
# UPDATE: simplified way more as of #8168. polymorphic adaption
# is turned off even if with_polymorphic is set, as long as there
# is no user-defined aliased selectable / subquery configured.
# this scales back the use of polymorphic adaption in practice
# to basically no cases except for concrete inheritance with a
# polymorphic base class.
#
return (
self._has_aliased_polymorphic_fromclause
or self._requires_row_aliasing
or (self.base_mapper._has_aliased_polymorphic_fromclause)
or self.base_mapper._requires_row_aliasing
)
@HasMemoized.memoized_attribute
def _with_polymorphic_mappers(self) -> Sequence[Mapper[Any]]:
self._check_configure()
if not self.with_polymorphic:
return []
return self._mappers_from_spec(*self.with_polymorphic)
@HasMemoized.memoized_attribute
def _post_inspect(self):
"""This hook is invoked by attribute inspection.
E.g. when Query calls:
coercions.expect(roles.ColumnsClauseRole, ent, keep_inspect=True)
This allows the inspection process run a configure mappers hook.
"""
self._check_configure()
@HasMemoized_ro_memoized_attribute
def _with_polymorphic_selectable(self) -> FromClause:
if not self.with_polymorphic:
return self.persist_selectable
spec, selectable = self.with_polymorphic
if selectable is not None:
return selectable
else:
return self._selectable_from_mappers(
self._mappers_from_spec(spec, selectable), False
)
with_polymorphic_mappers = _with_polymorphic_mappers
"""The list of :class:`_orm.Mapper` objects included in the
default "polymorphic" query.
"""
@HasMemoized_ro_memoized_attribute
def _insert_cols_evaluating_none(self):
return {
table: frozenset(
col for col in columns if col.type.should_evaluate_none
)
for table, columns in self._cols_by_table.items()
}
@HasMemoized.memoized_attribute
def _insert_cols_as_none(self):
return {
table: frozenset(
col.key
for col in columns
if not col.primary_key
and not col.server_default
and not col.default
and not col.type.should_evaluate_none
)
for table, columns in self._cols_by_table.items()
}
@HasMemoized.memoized_attribute
def _propkey_to_col(self):
return {
table: {self._columntoproperty[col].key: col for col in columns}
for table, columns in self._cols_by_table.items()
}
@HasMemoized.memoized_attribute
def _pk_keys_by_table(self):
return {
table: frozenset([col.key for col in pks])
for table, pks in self._pks_by_table.items()
}
@HasMemoized.memoized_attribute
def _pk_attr_keys_by_table(self):
return {
table: frozenset([self._columntoproperty[col].key for col in pks])
for table, pks in self._pks_by_table.items()
}
@HasMemoized.memoized_attribute
def _server_default_cols(
self,
) -> Mapping[FromClause, FrozenSet[Column[Any]]]:
return {
table: frozenset(
[
col
for col in cast("Iterable[Column[Any]]", columns)
if col.server_default is not None
or (
col.default is not None
and col.default.is_clause_element
)
]
)
for table, columns in self._cols_by_table.items()
}
@HasMemoized.memoized_attribute
def _server_onupdate_default_cols(
self,
) -> Mapping[FromClause, FrozenSet[Column[Any]]]:
return {
table: frozenset(
[
col
for col in cast("Iterable[Column[Any]]", columns)
if col.server_onupdate is not None
or (
col.onupdate is not None
and col.onupdate.is_clause_element
)
]
)
for table, columns in self._cols_by_table.items()
}
@HasMemoized.memoized_attribute
def _server_default_col_keys(self) -> Mapping[FromClause, FrozenSet[str]]:
return {
table: frozenset(col.key for col in cols if col.key is not None)
for table, cols in self._server_default_cols.items()
}
@HasMemoized.memoized_attribute
def _server_onupdate_default_col_keys(
self,
) -> Mapping[FromClause, FrozenSet[str]]:
return {
table: frozenset(col.key for col in cols if col.key is not None)
for table, cols in self._server_onupdate_default_cols.items()
}
@HasMemoized.memoized_attribute
def _server_default_plus_onupdate_propkeys(self) -> Set[str]:
result: Set[str] = set()
col_to_property = self._columntoproperty
for table, columns in self._server_default_cols.items():
result.update(
col_to_property[col].key
for col in columns.intersection(col_to_property)
)
for table, columns in self._server_onupdate_default_cols.items():
result.update(
col_to_property[col].key
for col in columns.intersection(col_to_property)
)
return result
@HasMemoized.memoized_instancemethod
def __clause_element__(self):
annotations: Dict[str, Any] = {
"entity_namespace": self,
"parententity": self,
"parentmapper": self,
}
if self.persist_selectable is not self.local_table:
# joined table inheritance, with polymorphic selectable,
# etc.
annotations["dml_table"] = self.local_table._annotate(
{
"entity_namespace": self,
"parententity": self,
"parentmapper": self,
}
)._set_propagate_attrs(
{"compile_state_plugin": "orm", "plugin_subject": self}
)
return self.selectable._annotate(annotations)._set_propagate_attrs(
{"compile_state_plugin": "orm", "plugin_subject": self}
)
@util.memoized_property
def select_identity_token(self):
return (
expression.null()
._annotate(
{
"entity_namespace": self,
"parententity": self,
"parentmapper": self,
"identity_token": True,
}
)
._set_propagate_attrs(
{"compile_state_plugin": "orm", "plugin_subject": self}
)
)
@property
def selectable(self) -> FromClause:
"""The :class:`_schema.FromClause` construct this
:class:`_orm.Mapper` selects from by default.
Normally, this is equivalent to :attr:`.persist_selectable`, unless
the ``with_polymorphic`` feature is in use, in which case the
full "polymorphic" selectable is returned.
"""
return self._with_polymorphic_selectable
def _with_polymorphic_args(
self,
spec: Any = None,
selectable: Union[Literal[False, None], FromClause] = False,
innerjoin: bool = False,
) -> Tuple[Sequence[Mapper[Any]], FromClause]:
if selectable not in (None, False):
selectable = coercions.expect(
roles.StrictFromClauseRole, selectable, allow_select=True
)
if self.with_polymorphic:
if not spec:
spec = self.with_polymorphic[0]
if selectable is False:
selectable = self.with_polymorphic[1]
elif selectable is False:
selectable = None
mappers = self._mappers_from_spec(spec, selectable)
if selectable is not None:
return mappers, selectable
else:
return mappers, self._selectable_from_mappers(mappers, innerjoin)
@HasMemoized.memoized_attribute
def _polymorphic_properties(self):
return list(
self._iterate_polymorphic_properties(
self._with_polymorphic_mappers
)
)
@property
def _all_column_expressions(self):
poly_properties = self._polymorphic_properties
adapter = self._polymorphic_adapter
return [
adapter.columns[c] if adapter else c
for prop in poly_properties
if isinstance(prop, properties.ColumnProperty)
and prop._renders_in_subqueries
for c in prop.columns
]
def _columns_plus_keys(self, polymorphic_mappers=()):
if polymorphic_mappers:
poly_properties = self._iterate_polymorphic_properties(
polymorphic_mappers
)
else:
poly_properties = self._polymorphic_properties
return [
(prop.key, prop.columns[0])
for prop in poly_properties
if isinstance(prop, properties.ColumnProperty)
]
@HasMemoized.memoized_attribute
def _polymorphic_adapter(self) -> Optional[orm_util.ORMAdapter]:
if self._has_aliased_polymorphic_fromclause:
return orm_util.ORMAdapter(
orm_util._TraceAdaptRole.MAPPER_POLYMORPHIC_ADAPTER,
self,
selectable=self.selectable,
equivalents=self._equivalent_columns,
limit_on_entity=False,
)
else:
return None
def _iterate_polymorphic_properties(self, mappers=None):
"""Return an iterator of MapperProperty objects which will render into
a SELECT."""
if mappers is None:
mappers = self._with_polymorphic_mappers
if not mappers:
for c in self.iterate_properties:
yield c
else:
# in the polymorphic case, filter out discriminator columns
# from other mappers, as these are sometimes dependent on that
# mapper's polymorphic selectable (which we don't want rendered)
for c in util.unique_list(
chain(
*[
list(mapper.iterate_properties)
for mapper in [self] + mappers
]
)
):
if getattr(c, "_is_polymorphic_discriminator", False) and (
self.polymorphic_on is None
or c.columns[0] is not self.polymorphic_on
):
continue
yield c
@HasMemoized.memoized_attribute
def attrs(self) -> util.ReadOnlyProperties[MapperProperty[Any]]:
"""A namespace of all :class:`.MapperProperty` objects
associated this mapper.
This is an object that provides each property based on
its key name. For instance, the mapper for a
``User`` class which has ``User.name`` attribute would
provide ``mapper.attrs.name``, which would be the
:class:`.ColumnProperty` representing the ``name``
column. The namespace object can also be iterated,
which would yield each :class:`.MapperProperty`.
:class:`_orm.Mapper` has several pre-filtered views
of this attribute which limit the types of properties
returned, including :attr:`.synonyms`, :attr:`.column_attrs`,
:attr:`.relationships`, and :attr:`.composites`.
.. warning::
The :attr:`_orm.Mapper.attrs` accessor namespace is an
instance of :class:`.OrderedProperties`. This is
a dictionary-like object which includes a small number of
named methods such as :meth:`.OrderedProperties.items`
and :meth:`.OrderedProperties.values`. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. ``mapper.attrs[somename]`` over
``getattr(mapper.attrs, somename)`` to avoid name collisions.
.. seealso::
:attr:`_orm.Mapper.all_orm_descriptors`
"""
self._check_configure()
return util.ReadOnlyProperties(self._props)
@HasMemoized.memoized_attribute
def all_orm_descriptors(self) -> util.ReadOnlyProperties[InspectionAttr]:
"""A namespace of all :class:`.InspectionAttr` attributes associated
with the mapped class.
These attributes are in all cases Python :term:`descriptors`
associated with the mapped class or its superclasses.
This namespace includes attributes that are mapped to the class
as well as attributes declared by extension modules.
It includes any Python descriptor type that inherits from
:class:`.InspectionAttr`. This includes
:class:`.QueryableAttribute`, as well as extension types such as
:class:`.hybrid_property`, :class:`.hybrid_method` and
:class:`.AssociationProxy`.
To distinguish between mapped attributes and extension attributes,
the attribute :attr:`.InspectionAttr.extension_type` will refer
to a constant that distinguishes between different extension types.
The sorting of the attributes is based on the following rules:
1. Iterate through the class and its superclasses in order from
subclass to superclass (i.e. iterate through ``cls.__mro__``)
2. For each class, yield the attributes in the order in which they
appear in ``__dict__``, with the exception of those in step
3 below. In Python 3.6 and above this ordering will be the
same as that of the class' construction, with the exception
of attributes that were added after the fact by the application
or the mapper.
3. If a certain attribute key is also in the superclass ``__dict__``,
then it's included in the iteration for that class, and not the
class in which it first appeared.
The above process produces an ordering that is deterministic in terms
of the order in which attributes were assigned to the class.
.. versionchanged:: 1.3.19 ensured deterministic ordering for
:meth:`_orm.Mapper.all_orm_descriptors`.
When dealing with a :class:`.QueryableAttribute`, the
:attr:`.QueryableAttribute.property` attribute refers to the
:class:`.MapperProperty` property, which is what you get when
referring to the collection of mapped properties via
:attr:`_orm.Mapper.attrs`.
.. warning::
The :attr:`_orm.Mapper.all_orm_descriptors`
accessor namespace is an
instance of :class:`.OrderedProperties`. This is
a dictionary-like object which includes a small number of
named methods such as :meth:`.OrderedProperties.items`
and :meth:`.OrderedProperties.values`. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. ``mapper.all_orm_descriptors[somename]`` over
``getattr(mapper.all_orm_descriptors, somename)`` to avoid name
collisions.
.. seealso::
:attr:`_orm.Mapper.attrs`
"""
return util.ReadOnlyProperties(
dict(self.class_manager._all_sqla_attributes())
)
@HasMemoized.memoized_attribute
@util.preload_module("sqlalchemy.orm.descriptor_props")
def _pk_synonyms(self) -> Dict[str, str]:
"""return a dictionary of {syn_attribute_name: pk_attr_name} for
all synonyms that refer to primary key columns
"""
descriptor_props = util.preloaded.orm_descriptor_props
pk_keys = {prop.key for prop in self._identity_key_props}
return {
syn.key: syn.name
for k, syn in self._props.items()
if isinstance(syn, descriptor_props.SynonymProperty)
and syn.name in pk_keys
}
@HasMemoized.memoized_attribute
@util.preload_module("sqlalchemy.orm.descriptor_props")
def synonyms(self) -> util.ReadOnlyProperties[SynonymProperty[Any]]:
"""Return a namespace of all :class:`.Synonym`
properties maintained by this :class:`_orm.Mapper`.
.. seealso::
:attr:`_orm.Mapper.attrs` - namespace of all
:class:`.MapperProperty`
objects.
"""
descriptor_props = util.preloaded.orm_descriptor_props
return self._filter_properties(descriptor_props.SynonymProperty)
@property
def entity_namespace(self):
return self.class_
@HasMemoized.memoized_attribute
def column_attrs(self) -> util.ReadOnlyProperties[ColumnProperty[Any]]:
"""Return a namespace of all :class:`.ColumnProperty`
properties maintained by this :class:`_orm.Mapper`.
.. seealso::
:attr:`_orm.Mapper.attrs` - namespace of all
:class:`.MapperProperty`
objects.
"""
return self._filter_properties(properties.ColumnProperty)
@HasMemoized.memoized_attribute
@util.preload_module("sqlalchemy.orm.relationships")
def relationships(
self,
) -> util.ReadOnlyProperties[RelationshipProperty[Any]]:
"""A namespace of all :class:`.Relationship` properties
maintained by this :class:`_orm.Mapper`.
.. warning::
the :attr:`_orm.Mapper.relationships` accessor namespace is an
instance of :class:`.OrderedProperties`. This is
a dictionary-like object which includes a small number of
named methods such as :meth:`.OrderedProperties.items`
and :meth:`.OrderedProperties.values`. When
accessing attributes dynamically, favor using the dict-access
scheme, e.g. ``mapper.relationships[somename]`` over
``getattr(mapper.relationships, somename)`` to avoid name
collisions.
.. seealso::
:attr:`_orm.Mapper.attrs` - namespace of all
:class:`.MapperProperty`
objects.
"""
return self._filter_properties(
util.preloaded.orm_relationships.RelationshipProperty
)
@HasMemoized.memoized_attribute
@util.preload_module("sqlalchemy.orm.descriptor_props")
def composites(self) -> util.ReadOnlyProperties[CompositeProperty[Any]]:
"""Return a namespace of all :class:`.Composite`
properties maintained by this :class:`_orm.Mapper`.
.. seealso::
:attr:`_orm.Mapper.attrs` - namespace of all
:class:`.MapperProperty`
objects.
"""
return self._filter_properties(
util.preloaded.orm_descriptor_props.CompositeProperty
)
def _filter_properties(
self, type_: Type[_MP]
) -> util.ReadOnlyProperties[_MP]:
self._check_configure()
return util.ReadOnlyProperties(
util.OrderedDict(
(k, v) for k, v in self._props.items() if isinstance(v, type_)
)
)
@HasMemoized.memoized_attribute
def _get_clause(self):
"""create a "get clause" based on the primary key. this is used
by query.get() and many-to-one lazyloads to load this item
by primary key.
"""
params = [
(
primary_key,
sql.bindparam("pk_%d" % idx, type_=primary_key.type),
)
for idx, primary_key in enumerate(self.primary_key, 1)
]
return (
sql.and_(*[k == v for (k, v) in params]),
util.column_dict(params),
)
@HasMemoized.memoized_attribute
def _equivalent_columns(self) -> _EquivalentColumnMap:
"""Create a map of all equivalent columns, based on
the determination of column pairs that are equated to
one another based on inherit condition. This is designed
to work with the queries that util.polymorphic_union
comes up with, which often don't include the columns from
the base table directly (including the subclass table columns
only).
The resulting structure is a dictionary of columns mapped
to lists of equivalent columns, e.g.::
{
tablea.col1:
{tableb.col1, tablec.col1},
tablea.col2:
{tabled.col2}
}
"""
result: _EquivalentColumnMap = {}
def visit_binary(binary):
if binary.operator == operators.eq:
if binary.left in result:
result[binary.left].add(binary.right)
else:
result[binary.left] = {binary.right}
if binary.right in result:
result[binary.right].add(binary.left)
else:
result[binary.right] = {binary.left}
for mapper in self.base_mapper.self_and_descendants:
if mapper.inherit_condition is not None:
visitors.traverse(
mapper.inherit_condition, {}, {"binary": visit_binary}
)
return result
def _is_userland_descriptor(self, assigned_name: str, obj: Any) -> bool:
if isinstance(
obj,
(
_MappedAttribute,
instrumentation.ClassManager,
expression.ColumnElement,
),
):
return False
else:
return assigned_name not in self._dataclass_fields
@HasMemoized.memoized_attribute
def _dataclass_fields(self):
return [f.name for f in util.dataclass_fields(self.class_)]
def _should_exclude(self, name, assigned_name, local, column):
"""determine whether a particular property should be implicitly
present on the class.
This occurs when properties are propagated from an inherited class, or
are applied from the columns present in the mapped table.
"""
if column is not None and sql_base._never_select_column(column):
return True
# check for class-bound attributes and/or descriptors,
# either local or from an inherited class
# ignore dataclass field default values
if local:
if self.class_.__dict__.get(
assigned_name, None
) is not None and self._is_userland_descriptor(
assigned_name, self.class_.__dict__[assigned_name]
):
return True
else:
attr = self.class_manager._get_class_attr_mro(assigned_name, None)
if attr is not None and self._is_userland_descriptor(
assigned_name, attr
):
return True
if (
self.include_properties is not None
and name not in self.include_properties
and (column is None or column not in self.include_properties)
):
self._log("not including property %s" % (name))
return True
if self.exclude_properties is not None and (
name in self.exclude_properties
or (column is not None and column in self.exclude_properties)
):
self._log("excluding property %s" % (name))
return True
return False
def common_parent(self, other: Mapper[Any]) -> bool:
"""Return true if the given mapper shares a
common inherited parent as this mapper."""
return self.base_mapper is other.base_mapper
def is_sibling(self, other: Mapper[Any]) -> bool:
"""return true if the other mapper is an inheriting sibling to this
one. common parent but different branch
"""
return (
self.base_mapper is other.base_mapper
and not self.isa(other)
and not other.isa(self)
)
def _canload(
self, state: InstanceState[Any], allow_subtypes: bool
) -> bool:
s = self.primary_mapper()
if self.polymorphic_on is not None or allow_subtypes:
return _state_mapper(state).isa(s)
else:
return _state_mapper(state) is s
def isa(self, other: Mapper[Any]) -> bool:
"""Return True if the this mapper inherits from the given mapper."""
m: Optional[Mapper[Any]] = self
while m and m is not other:
m = m.inherits
return bool(m)
def iterate_to_root(self) -> Iterator[Mapper[Any]]:
m: Optional[Mapper[Any]] = self
while m:
yield m
m = m.inherits
@HasMemoized.memoized_attribute
def self_and_descendants(self) -> Sequence[Mapper[Any]]:
"""The collection including this mapper and all descendant mappers.
This includes not just the immediately inheriting mappers but
all their inheriting mappers as well.
"""
descendants = []
stack = deque([self])
while stack:
item = stack.popleft()
descendants.append(item)
stack.extend(item._inheriting_mappers)
return util.WeakSequence(descendants)
def polymorphic_iterator(self) -> Iterator[Mapper[Any]]:
"""Iterate through the collection including this mapper and
all descendant mappers.
This includes not just the immediately inheriting mappers but
all their inheriting mappers as well.
To iterate through an entire hierarchy, use
``mapper.base_mapper.polymorphic_iterator()``.
"""
return iter(self.self_and_descendants)
def primary_mapper(self) -> Mapper[Any]:
"""Return the primary mapper corresponding to this mapper's class key
(class)."""
return self.class_manager.mapper
@property
def primary_base_mapper(self) -> Mapper[Any]:
return self.class_manager.mapper.base_mapper
def _result_has_identity_key(self, result, adapter=None):
pk_cols: Sequence[ColumnClause[Any]] = self.primary_key
if adapter:
pk_cols = [adapter.columns[c] for c in pk_cols]
rk = result.keys()
for col in pk_cols:
if col not in rk:
return False
else:
return True
def identity_key_from_row(
self,
row: Optional[Union[Row[Any], RowMapping]],
identity_token: Optional[Any] = None,
adapter: Optional[ORMAdapter] = None,
) -> _IdentityKeyType[_O]:
"""Return an identity-map key for use in storing/retrieving an
item from the identity map.
:param row: A :class:`.Row` or :class:`.RowMapping` produced from a
result set that selected from the ORM mapped primary key columns.
.. versionchanged:: 2.0
:class:`.Row` or :class:`.RowMapping` are accepted
for the "row" argument
"""
pk_cols: Sequence[ColumnClause[Any]] = self.primary_key
if adapter:
pk_cols = [adapter.columns[c] for c in pk_cols]
if hasattr(row, "_mapping"):
mapping = row._mapping # type: ignore
else:
mapping = cast("Mapping[Any, Any]", row)
return (
self._identity_class,
tuple(mapping[column] for column in pk_cols), # type: ignore
identity_token,
)
def identity_key_from_primary_key(
self,
primary_key: Tuple[Any, ...],
identity_token: Optional[Any] = None,
) -> _IdentityKeyType[_O]:
"""Return an identity-map key for use in storing/retrieving an
item from an identity map.
:param primary_key: A list of values indicating the identifier.
"""
return (
self._identity_class,
tuple(primary_key),
identity_token,
)
def identity_key_from_instance(self, instance: _O) -> _IdentityKeyType[_O]:
"""Return the identity key for the given instance, based on
its primary key attributes.
If the instance's state is expired, calling this method
will result in a database check to see if the object has been deleted.
If the row no longer exists,
:class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
This value is typically also found on the instance state under the
attribute name `key`.
"""
state = attributes.instance_state(instance)
return self._identity_key_from_state(state, PassiveFlag.PASSIVE_OFF)
def _identity_key_from_state(
self,
state: InstanceState[_O],
passive: PassiveFlag = PassiveFlag.PASSIVE_RETURN_NO_VALUE,
) -> _IdentityKeyType[_O]:
dict_ = state.dict
manager = state.manager
return (
self._identity_class,
tuple(
[
manager[prop.key].impl.get(state, dict_, passive)
for prop in self._identity_key_props
]
),
state.identity_token,
)
def primary_key_from_instance(self, instance: _O) -> Tuple[Any, ...]:
"""Return the list of primary key values for the given
instance.
If the instance's state is expired, calling this method
will result in a database check to see if the object has been deleted.
If the row no longer exists,
:class:`~sqlalchemy.orm.exc.ObjectDeletedError` is raised.
"""
state = attributes.instance_state(instance)
identity_key = self._identity_key_from_state(
state, PassiveFlag.PASSIVE_OFF
)
return identity_key[1]
@HasMemoized.memoized_attribute
def _persistent_sortkey_fn(self):
key_fns = [col.type.sort_key_function for col in self.primary_key]
if set(key_fns).difference([None]):
def key(state):
return tuple(
key_fn(val) if key_fn is not None else val
for key_fn, val in zip(key_fns, state.key[1])
)
else:
def key(state):
return state.key[1]
return key
@HasMemoized.memoized_attribute
def _identity_key_props(self):
return [self._columntoproperty[col] for col in self.primary_key]
@HasMemoized.memoized_attribute
def _all_pk_cols(self):
collection: Set[ColumnClause[Any]] = set()
for table in self.tables:
collection.update(self._pks_by_table[table])
return collection
@HasMemoized.memoized_attribute
def _should_undefer_in_wildcard(self):
cols: Set[ColumnElement[Any]] = set(self.primary_key)
if self.polymorphic_on is not None:
cols.add(self.polymorphic_on)
return cols
@HasMemoized.memoized_attribute
def _primary_key_propkeys(self):
return {self._columntoproperty[col].key for col in self._all_pk_cols}
def _get_state_attr_by_column(
self,
state: InstanceState[_O],
dict_: _InstanceDict,
column: ColumnElement[Any],
passive: PassiveFlag = PassiveFlag.PASSIVE_RETURN_NO_VALUE,
) -> Any:
prop = self._columntoproperty[column]
return state.manager[prop.key].impl.get(state, dict_, passive=passive)
def _set_committed_state_attr_by_column(self, state, dict_, column, value):
prop = self._columntoproperty[column]
state.manager[prop.key].impl.set_committed_value(state, dict_, value)
def _set_state_attr_by_column(self, state, dict_, column, value):
prop = self._columntoproperty[column]
state.manager[prop.key].impl.set(state, dict_, value, None)
def _get_committed_attr_by_column(self, obj, column):
state = attributes.instance_state(obj)
dict_ = attributes.instance_dict(obj)
return self._get_committed_state_attr_by_column(
state, dict_, column, passive=PassiveFlag.PASSIVE_OFF
)
def _get_committed_state_attr_by_column(
self, state, dict_, column, passive=PassiveFlag.PASSIVE_RETURN_NO_VALUE
):
prop = self._columntoproperty[column]
return state.manager[prop.key].impl.get_committed_value(
state, dict_, passive=passive
)
def _optimized_get_statement(self, state, attribute_names):
"""assemble a WHERE clause which retrieves a given state by primary
key, using a minimized set of tables.
Applies to a joined-table inheritance mapper where the
requested attribute names are only present on joined tables,
not the base table. The WHERE clause attempts to include
only those tables to minimize joins.
"""
props = self._props
col_attribute_names = set(attribute_names).intersection(
state.mapper.column_attrs.keys()
)
tables: Set[FromClause] = set(
chain(
*[
sql_util.find_tables(c, check_columns=True)
for key in col_attribute_names
for c in props[key].columns
]
)
)
if self.base_mapper.local_table in tables:
return None
def visit_binary(binary):
leftcol = binary.left
rightcol = binary.right
if leftcol is None or rightcol is None:
return
if leftcol.table not in tables:
leftval = self._get_committed_state_attr_by_column(
state,
state.dict,
leftcol,
passive=PassiveFlag.PASSIVE_NO_INITIALIZE,
)
if leftval in orm_util._none_set:
raise _OptGetColumnsNotAvailable()
binary.left = sql.bindparam(
None, leftval, type_=binary.right.type
)
elif rightcol.table not in tables:
rightval = self._get_committed_state_attr_by_column(
state,
state.dict,
rightcol,
passive=PassiveFlag.PASSIVE_NO_INITIALIZE,
)
if rightval in orm_util._none_set:
raise _OptGetColumnsNotAvailable()
binary.right = sql.bindparam(
None, rightval, type_=binary.right.type
)
allconds: List[ColumnElement[bool]] = []
start = False
# as of #7507, from the lowest base table on upwards,
# we include all intermediary tables.
for mapper in reversed(list(self.iterate_to_root())):
if mapper.local_table in tables:
start = True
elif not isinstance(mapper.local_table, expression.TableClause):
return None
if start and not mapper.single:
assert mapper.inherits
assert not mapper.concrete
assert mapper.inherit_condition is not None
allconds.append(mapper.inherit_condition)
tables.add(mapper.local_table)
# only the bottom table needs its criteria to be altered to fit
# the primary key ident - the rest of the tables upwards to the
# descendant-most class should all be present and joined to each
# other.
try:
_traversed = visitors.cloned_traverse(
allconds[0], {}, {"binary": visit_binary}
)
except _OptGetColumnsNotAvailable:
return None
else:
allconds[0] = _traversed
cond = sql.and_(*allconds)
cols = []
for key in col_attribute_names:
cols.extend(props[key].columns)
return (
sql.select(*cols)
.where(cond)
.set_label_style(LABEL_STYLE_TABLENAME_PLUS_COL)
)
def _iterate_to_target_viawpoly(self, mapper):
if self.isa(mapper):
prev = self
for m in self.iterate_to_root():
yield m
if m is not prev and prev not in m._with_polymorphic_mappers:
break
prev = m
if m is mapper:
break
@HasMemoized.memoized_attribute
def _would_selectinload_combinations_cache(self):
return {}
def _would_selectin_load_only_from_given_mapper(self, super_mapper):
"""return True if this mapper would "selectin" polymorphic load based
on the given super mapper, and not from a setting from a subclass.
given::
class A:
...
class B(A):
__mapper_args__ = {"polymorphic_load": "selectin"}
class C(B):
...
class D(B):
__mapper_args__ = {"polymorphic_load": "selectin"}
``inspect(C)._would_selectin_load_only_from_given_mapper(inspect(B))``
returns True, because C does selectin loading because of B's setting.
OTOH, ``inspect(D)
._would_selectin_load_only_from_given_mapper(inspect(B))``
returns False, because D does selectin loading because of its own
setting; when we are doing a selectin poly load from B, we want to
filter out D because it would already have its own selectin poly load
set up separately.
Added as part of #9373.
"""
cache = self._would_selectinload_combinations_cache
try:
return cache[super_mapper]
except KeyError:
pass
# assert that given object is a supermapper, meaning we already
# strong reference it directly or indirectly. this allows us
# to not worry that we are creating new strongrefs to unrelated
# mappers or other objects.
assert self.isa(super_mapper)
mapper = super_mapper
for m in self._iterate_to_target_viawpoly(mapper):
if m.polymorphic_load == "selectin":
retval = m is super_mapper
break
else:
retval = False
cache[super_mapper] = retval
return retval
def _should_selectin_load(self, enabled_via_opt, polymorphic_from):
if not enabled_via_opt:
# common case, takes place for all polymorphic loads
mapper = polymorphic_from
for m in self._iterate_to_target_viawpoly(mapper):
if m.polymorphic_load == "selectin":
return m
else:
# uncommon case, selectin load options were used
enabled_via_opt = set(enabled_via_opt)
enabled_via_opt_mappers = {e.mapper: e for e in enabled_via_opt}
for entity in enabled_via_opt.union([polymorphic_from]):
mapper = entity.mapper
for m in self._iterate_to_target_viawpoly(mapper):
if (
m.polymorphic_load == "selectin"
or m in enabled_via_opt_mappers
):
return enabled_via_opt_mappers.get(m, m)
return None
@util.preload_module("sqlalchemy.orm.strategy_options")
def _subclass_load_via_in(self, entity, polymorphic_from):
"""Assemble a that can load the columns local to
this subclass as a SELECT with IN.
"""
strategy_options = util.preloaded.orm_strategy_options
assert self.inherits
if self.polymorphic_on is not None:
polymorphic_prop = self._columntoproperty[self.polymorphic_on]
keep_props = set([polymorphic_prop] + self._identity_key_props)
else:
keep_props = set(self._identity_key_props)
disable_opt = strategy_options.Load(entity)
enable_opt = strategy_options.Load(entity)
classes_to_include = {self}
m: Optional[Mapper[Any]] = self.inherits
while (
m is not None
and m is not polymorphic_from
and m.polymorphic_load == "selectin"
):
classes_to_include.add(m)
m = m.inherits
for prop in self.column_attrs + self.relationships:
# skip prop keys that are not instrumented on the mapped class.
# this is primarily the "_sa_polymorphic_on" property that gets
# created for an ad-hoc polymorphic_on SQL expression, issue #8704
if prop.key not in self.class_manager:
continue
if prop.parent in classes_to_include or prop in keep_props:
# "enable" options, to turn on the properties that we want to
# load by default (subject to options from the query)
if not isinstance(prop, StrategizedProperty):
continue
enable_opt = enable_opt._set_generic_strategy(
# convert string name to an attribute before passing
# to loader strategy. note this must be in terms
# of given entity, such as AliasedClass, etc.
(getattr(entity.entity_namespace, prop.key),),
dict(prop.strategy_key),
_reconcile_to_other=True,
)
else:
# "disable" options, to turn off the properties from the
# superclass that we *don't* want to load, applied after
# the options from the query to override them
disable_opt = disable_opt._set_generic_strategy(
# convert string name to an attribute before passing
# to loader strategy. note this must be in terms
# of given entity, such as AliasedClass, etc.
(getattr(entity.entity_namespace, prop.key),),
{"do_nothing": True},
_reconcile_to_other=False,
)
primary_key = [
sql_util._deep_annotate(pk, {"_orm_adapt": True})
for pk in self.primary_key
]
in_expr: ColumnElement[Any]
if len(primary_key) > 1:
in_expr = sql.tuple_(*primary_key)
else:
in_expr = primary_key[0]
if entity.is_aliased_class:
assert entity.mapper is self
q = sql.select(entity).set_label_style(
LABEL_STYLE_TABLENAME_PLUS_COL
)
in_expr = entity._adapter.traverse(in_expr)
primary_key = [entity._adapter.traverse(k) for k in primary_key]
q = q.where(
in_expr.in_(sql.bindparam("primary_keys", expanding=True))
).order_by(*primary_key)
else:
q = sql.select(self).set_label_style(
LABEL_STYLE_TABLENAME_PLUS_COL
)
q = q.where(
in_expr.in_(sql.bindparam("primary_keys", expanding=True))
).order_by(*primary_key)
return q, enable_opt, disable_opt
@HasMemoized.memoized_attribute
def _subclass_load_via_in_mapper(self):
# the default is loading this mapper against the basemost mapper
return self._subclass_load_via_in(self, self.base_mapper)
def cascade_iterator(
self,
type_: str,
state: InstanceState[_O],
halt_on: Optional[Callable[[InstanceState[Any]], bool]] = None,
) -> Iterator[
Tuple[object, Mapper[Any], InstanceState[Any], _InstanceDict]
]:
r"""Iterate each element and its mapper in an object graph,
for all relationships that meet the given cascade rule.
:param type\_:
The name of the cascade rule (i.e. ``"save-update"``, ``"delete"``,
etc.).
.. note:: the ``"all"`` cascade is not accepted here. For a generic
object traversal function, see :ref:`faq_walk_objects`.
:param state:
The lead InstanceState. child items will be processed per
the relationships defined for this object's mapper.
:return: the method yields individual object instances.
.. seealso::
:ref:`unitofwork_cascades`
:ref:`faq_walk_objects` - illustrates a generic function to
traverse all objects without relying on cascades.
"""
visited_states: Set[InstanceState[Any]] = set()
prp, mpp = object(), object()
assert state.mapper.isa(self)
# this is actually a recursive structure, fully typing it seems
# a little too difficult for what it's worth here
visitables: Deque[
Tuple[
Deque[Any],
object,
Optional[InstanceState[Any]],
Optional[_InstanceDict],
]
]
visitables = deque(
[(deque(state.mapper._props.values()), prp, state, state.dict)]
)
while visitables:
iterator, item_type, parent_state, parent_dict = visitables[-1]
if not iterator:
visitables.pop()
continue
if item_type is prp:
prop = iterator.popleft()
if not prop.cascade or type_ not in prop.cascade:
continue
assert parent_state is not None
assert parent_dict is not None
queue = deque(
prop.cascade_iterator(
type_,
parent_state,
parent_dict,
visited_states,
halt_on,
)
)
if queue:
visitables.append((queue, mpp, None, None))
elif item_type is mpp:
(
instance,
instance_mapper,
corresponding_state,
corresponding_dict,
) = iterator.popleft()
yield (
instance,
instance_mapper,
corresponding_state,
corresponding_dict,
)
visitables.append(
(
deque(instance_mapper._props.values()),
prp,
corresponding_state,
corresponding_dict,
)
)
@HasMemoized.memoized_attribute
def _compiled_cache(self):
return util.LRUCache(self._compiled_cache_size)
@HasMemoized.memoized_attribute
def _multiple_persistence_tables(self):
return len(self.tables) > 1
@HasMemoized.memoized_attribute
def _sorted_tables(self):
table_to_mapper: Dict[TableClause, Mapper[Any]] = {}
for mapper in self.base_mapper.self_and_descendants:
for t in mapper.tables:
table_to_mapper.setdefault(t, mapper)
extra_dependencies = []
for table, mapper in table_to_mapper.items():
super_ = mapper.inherits
if super_:
extra_dependencies.extend(
[(super_table, table) for super_table in super_.tables]
)
def skip(fk):
# attempt to skip dependencies that are not
# significant to the inheritance chain
# for two tables that are related by inheritance.
# while that dependency may be important, it's technically
# not what we mean to sort on here.
parent = table_to_mapper.get(fk.parent.table)
dep = table_to_mapper.get(fk.column.table)
if (
parent is not None
and dep is not None
and dep is not parent
and dep.inherit_condition is not None
):
cols = set(sql_util._find_columns(dep.inherit_condition))
if parent.inherit_condition is not None:
cols = cols.union(
sql_util._find_columns(parent.inherit_condition)
)
return fk.parent not in cols and fk.column not in cols
else:
return fk.parent not in cols
return False
sorted_ = sql_util.sort_tables(
table_to_mapper,
skip_fn=skip,
extra_dependencies=extra_dependencies,
)
ret = util.OrderedDict()
for t in sorted_:
ret[t] = table_to_mapper[t]
return ret
def _memo(self, key: Any, callable_: Callable[[], _T]) -> _T:
if key in self._memoized_values:
return cast(_T, self._memoized_values[key])
else:
self._memoized_values[key] = value = callable_()
return value
@util.memoized_property
def _table_to_equated(self):
"""memoized map of tables to collections of columns to be
synchronized upwards to the base mapper."""
result: util.defaultdict[
Table,
List[
Tuple[
Mapper[Any],
List[Tuple[ColumnElement[Any], ColumnElement[Any]]],
]
],
] = util.defaultdict(list)
def set_union(x, y):
return x.union(y)
for table in self._sorted_tables:
cols = set(table.c)
for m in self.iterate_to_root():
if m._inherits_equated_pairs and cols.intersection(
reduce(
set_union,
[l.proxy_set for l, r in m._inherits_equated_pairs],
)
):
result[table].append((m, m._inherits_equated_pairs))
return result
class _OptGetColumnsNotAvailable(Exception):
pass
def configure_mappers() -> None:
"""Initialize the inter-mapper relationships of all mappers that
have been constructed thus far across all :class:`_orm.registry`
collections.
The configure step is used to reconcile and initialize the
:func:`_orm.relationship` linkages between mapped classes, as well as to
invoke configuration events such as the
:meth:`_orm.MapperEvents.before_configured` and
:meth:`_orm.MapperEvents.after_configured`, which may be used by ORM
extensions or user-defined extension hooks.
Mapper configuration is normally invoked automatically, the first time
mappings from a particular :class:`_orm.registry` are used, as well as
whenever mappings are used and additional not-yet-configured mappers have
been constructed. The automatic configuration process however is local only
to the :class:`_orm.registry` involving the target mapper and any related
:class:`_orm.registry` objects which it may depend on; this is
equivalent to invoking the :meth:`_orm.registry.configure` method
on a particular :class:`_orm.registry`.
By contrast, the :func:`_orm.configure_mappers` function will invoke the
configuration process on all :class:`_orm.registry` objects that
exist in memory, and may be useful for scenarios where many individual
:class:`_orm.registry` objects that are nonetheless interrelated are
in use.
.. versionchanged:: 1.4
As of SQLAlchemy 1.4.0b2, this function works on a
per-:class:`_orm.registry` basis, locating all :class:`_orm.registry`
objects present and invoking the :meth:`_orm.registry.configure` method
on each. The :meth:`_orm.registry.configure` method may be preferred to
limit the configuration of mappers to those local to a particular
:class:`_orm.registry` and/or declarative base class.
Points at which automatic configuration is invoked include when a mapped
class is instantiated into an instance, as well as when ORM queries
are emitted using :meth:`.Session.query` or :meth:`_orm.Session.execute`
with an ORM-enabled statement.
The mapper configure process, whether invoked by
:func:`_orm.configure_mappers` or from :meth:`_orm.registry.configure`,
provides several event hooks that can be used to augment the mapper
configuration step. These hooks include:
* :meth:`.MapperEvents.before_configured` - called once before
:func:`.configure_mappers` or :meth:`_orm.registry.configure` does any
work; this can be used to establish additional options, properties, or
related mappings before the operation proceeds.
* :meth:`.MapperEvents.mapper_configured` - called as each individual
:class:`_orm.Mapper` is configured within the process; will include all
mapper state except for backrefs set up by other mappers that are still
to be configured.
* :meth:`.MapperEvents.after_configured` - called once after
:func:`.configure_mappers` or :meth:`_orm.registry.configure` is
complete; at this stage, all :class:`_orm.Mapper` objects that fall
within the scope of the configuration operation will be fully configured.
Note that the calling application may still have other mappings that
haven't been produced yet, such as if they are in modules as yet
unimported, and may also have mappings that are still to be configured,
if they are in other :class:`_orm.registry` collections not part of the
current scope of configuration.
"""
_configure_registries(_all_registries(), cascade=True)
def _configure_registries(
registries: Set[_RegistryType], cascade: bool
) -> None:
for reg in registries:
if reg._new_mappers:
break
else:
return
with _CONFIGURE_MUTEX:
global _already_compiling
if _already_compiling:
return
_already_compiling = True
try:
# double-check inside mutex
for reg in registries:
if reg._new_mappers:
break
else:
return
Mapper.dispatch._for_class(Mapper).before_configured() # type: ignore # noqa: E501
# initialize properties on all mappers
# note that _mapper_registry is unordered, which
# may randomly conceal/reveal issues related to
# the order of mapper compilation
_do_configure_registries(registries, cascade)
finally:
_already_compiling = False
Mapper.dispatch._for_class(Mapper).after_configured() # type: ignore
@util.preload_module("sqlalchemy.orm.decl_api")
def _do_configure_registries(
registries: Set[_RegistryType], cascade: bool
) -> None:
registry = util.preloaded.orm_decl_api.registry
orig = set(registries)
for reg in registry._recurse_with_dependencies(registries):
has_skip = False
for mapper in reg._mappers_to_configure():
run_configure = None
for fn in mapper.dispatch.before_mapper_configured:
run_configure = fn(mapper, mapper.class_)
if run_configure is EXT_SKIP:
has_skip = True
break
if run_configure is EXT_SKIP:
continue
if getattr(mapper, "_configure_failed", False):
e = sa_exc.InvalidRequestError(
"One or more mappers failed to initialize - "
"can't proceed with initialization of other "
"mappers. Triggering mapper: '%s'. "
"Original exception was: %s"
% (mapper, mapper._configure_failed)
)
e._configure_failed = mapper._configure_failed # type: ignore
raise e
if not mapper.configured:
try:
mapper._post_configure_properties()
mapper._expire_memoizations()
mapper.dispatch.mapper_configured(mapper, mapper.class_)
except Exception:
exc = sys.exc_info()[1]
if not hasattr(exc, "_configure_failed"):
mapper._configure_failed = exc
raise
if not has_skip:
reg._new_mappers = False
if not cascade and reg._dependencies.difference(orig):
raise sa_exc.InvalidRequestError(
"configure was called with cascade=False but "
"additional registries remain"
)
@util.preload_module("sqlalchemy.orm.decl_api")
def _dispose_registries(registries: Set[_RegistryType], cascade: bool) -> None:
registry = util.preloaded.orm_decl_api.registry
orig = set(registries)
for reg in registry._recurse_with_dependents(registries):
if not cascade and reg._dependents.difference(orig):
raise sa_exc.InvalidRequestError(
"Registry has dependent registries that are not disposed; "
"pass cascade=True to clear these also"
)
while reg._managers:
try:
manager, _ = reg._managers.popitem()
except KeyError:
# guard against race between while and popitem
pass
else:
reg._dispose_manager_and_mapper(manager)
reg._non_primary_mappers.clear()
reg._dependents.clear()
for dep in reg._dependencies:
dep._dependents.discard(reg)
reg._dependencies.clear()
# this wasn't done in the 1.3 clear_mappers() and in fact it
# was a bug, as it could cause configure_mappers() to invoke
# the "before_configured" event even though mappers had all been
# disposed.
reg._new_mappers = False
def reconstructor(fn):
"""Decorate a method as the 'reconstructor' hook.
Designates a single method as the "reconstructor", an ``__init__``-like
method that will be called by the ORM after the instance has been
loaded from the database or otherwise reconstituted.
.. tip::
The :func:`_orm.reconstructor` decorator makes use of the
:meth:`_orm.InstanceEvents.load` event hook, which can be
used directly.
The reconstructor will be invoked with no arguments. Scalar
(non-collection) database-mapped attributes of the instance will
be available for use within the function. Eagerly-loaded
collections are generally not yet available and will usually only
contain the first element. ORM state changes made to objects at
this stage will not be recorded for the next flush() operation, so
the activity within a reconstructor should be conservative.
.. seealso::
:meth:`.InstanceEvents.load`
"""
fn.__sa_reconstructor__ = True
return fn
def validates(
*names: str, include_removes: bool = False, include_backrefs: bool = True
) -> Callable[[_Fn], _Fn]:
r"""Decorate a method as a 'validator' for one or more named properties.
Designates a method as a validator, a method which receives the
name of the attribute as well as a value to be assigned, or in the
case of a collection, the value to be added to the collection.
The function can then raise validation exceptions to halt the
process from continuing (where Python's built-in ``ValueError``
and ``AssertionError`` exceptions are reasonable choices), or can
modify or replace the value before proceeding. The function should
otherwise return the given value.
Note that a validator for a collection **cannot** issue a load of that
collection within the validation routine - this usage raises
an assertion to avoid recursion overflows. This is a reentrant
condition which is not supported.
:param \*names: list of attribute names to be validated.
:param include_removes: if True, "remove" events will be
sent as well - the validation function must accept an additional
argument "is_remove" which will be a boolean.
:param include_backrefs: defaults to ``True``; if ``False``, the
validation function will not emit if the originator is an attribute
event related via a backref. This can be used for bi-directional
:func:`.validates` usage where only one validator should emit per
attribute operation.
.. versionchanged:: 2.0.16 This paramter inadvertently defaulted to
``False`` for releases 2.0.0 through 2.0.15. Its correct default
of ``True`` is restored in 2.0.16.
.. seealso::
:ref:`simple_validators` - usage examples for :func:`.validates`
"""
def wrap(fn: _Fn) -> _Fn:
fn.__sa_validators__ = names # type: ignore[attr-defined]
fn.__sa_validation_opts__ = { # type: ignore[attr-defined]
"include_removes": include_removes,
"include_backrefs": include_backrefs,
}
return fn
return wrap
def _event_on_load(state, ctx):
instrumenting_mapper = state.manager.mapper
if instrumenting_mapper._reconstructor:
instrumenting_mapper._reconstructor(state.obj())
def _event_on_init(state, args, kwargs):
"""Run init_instance hooks.
This also includes mapper compilation, normally not needed
here but helps with some piecemeal configuration
scenarios (such as in the ORM tutorial).
"""
instrumenting_mapper = state.manager.mapper
if instrumenting_mapper:
instrumenting_mapper._check_configure()
if instrumenting_mapper._set_polymorphic_identity:
instrumenting_mapper._set_polymorphic_identity(state)
class _ColumnMapping(Dict["ColumnElement[Any]", "MapperProperty[Any]"]):
"""Error reporting helper for mapper._columntoproperty."""
__slots__ = ("mapper",)
def __init__(self, mapper):
# TODO: weakref would be a good idea here
self.mapper = mapper
def __missing__(self, column):
prop = self.mapper._props.get(column)
if prop:
raise orm_exc.UnmappedColumnError(
"Column '%s.%s' is not available, due to "
"conflicting property '%s':%r"
% (column.table.name, column.name, column.key, prop)
)
raise orm_exc.UnmappedColumnError(
"No column %s is configured on mapper %s..."
% (column, self.mapper)
)