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Edit File: mapper.py
# orm/mapper.py # Copyright (C) 2005-2023 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 """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 absolute_import from collections import deque from itertools import chain import sys 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 .base import _class_to_mapper from .base import _state_mapper from .base import class_mapper 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 ..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 util as sql_util from ..sql import visitors from ..sql.selectable import LABEL_STYLE_TABLENAME_PLUS_COL from ..util import HasMemoized _mapper_registries = weakref.WeakKeyDictionary() _legacy_registry = None def _all_registries(): with _CONFIGURE_MUTEX: return set(_mapper_registries) def _unconfigured_mappers(): for reg in _all_registries(): for mapper in reg._mappers_to_configure(): yield mapper _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 = util.threading.RLock() @inspection._self_inspects @log.class_logger class Mapper( ORMFromClauseRole, ORMEntityColumnsClauseRole, sql_base.MemoizedHasCacheKey, InspectionAttr, ): """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`. """ _dispose_called = 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_, local_table=None, properties=None, primary_key=None, non_primary=False, inherits=None, inherit_condition=None, inherit_foreign_keys=None, always_refresh=False, version_id_col=None, version_id_generator=None, polymorphic_on=None, _polymorphic_map=None, polymorphic_identity=None, concrete=False, with_polymorphic=None, polymorphic_load=None, allow_partial_pks=True, batch=True, column_prefix=None, include_properties=None, exclude_properties=None, passive_updates=True, passive_deletes=False, confirm_deleted_rows=True, eager_defaults=False, legacy_is_orphan=False, _compiled_cache_size=100, ): r"""Direct constructor for a new :class:`_orm.Mapper` object. The :func:`_orm.mapper` function 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:: 1.4 The :func:`_orm.mapper` function should not be called directly for classical mapping; for a classical mapping configuration, use the :meth:`_orm.registry.map_imperatively` method. The :func:`_orm.mapper` function may become private in a future release. 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 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 ``__table__`` argument or via the :class:`_schema.Table` produced as a result of the ``__tablename__`` and :class:`_schema.Column` arguments present. :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. .. versionadded:: 0.9.4 - added :paramref:`.mapper.confirm_deleted_rows` as well as conditional matched row checking on delete. :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. By default, this scheme will emit an individual ``SELECT`` statement per row inserted or updated, which note can add significant performance overhead. However, if the target database supports :term:`RETURNING`, the default values will be returned inline with the INSERT or UPDATE statement, which can greatly enhance performance for an application that needs frequent access to just-generated server defaults. .. seealso:: :ref:`orm_server_defaults` .. versionchanged:: 0.9.0 The ``eager_defaults`` option can now make use of :term:`RETURNING` for backends which support it. :param exclude_properties: A list or set of string column names to be excluded from mapping. See :ref:`include_exclude_cols` for an example. :param include_properties: An inclusive list or set of string column names to map. See :ref:`include_exclude_cols` for an example. :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. .. versionadded:: 1.1 .. 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. This value is commonly a :class:`_schema.Column` object that's present in the mapped :class:`_schema.Table`:: class Employee(Base): __tablename__ = 'employee' id = Column(Integer, primary_key=True) discriminator = 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 = Column(Integer, primary_key=True) discriminator = 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 configured with :func:`.column_property`, or to the string name of one:: class Employee(Base): __tablename__ = 'employee' id = Column(Integer, primary_key=True) discriminator = Column(String(50)) employee_type = column_property( case([ (discriminator == "EN", "engineer"), (discriminator == "MA", "manager"), ], else_="employee") ) __mapper_args__ = { "polymorphic_on":employee_type, "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 ``polymorphic_on`` setting. As rows are received, the value corresponding to the ``polymorphic_on`` column expression is compared to this value, indicating which subclass should be used for the newly reconstructed object. :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 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. .. 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. .. versionadded:: 0.9.0 ``version_id_generator`` supports server-side version number generation. .. 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. .. seealso:: :ref:`with_polymorphic` - discussion of polymorphic querying techniques. """ self.class_ = util.assert_arg_type(class_, type, "class_") self._sort_key = "%s.%s" % ( self.class_.__module__, self.class_.__name__, ) self.class_manager = None 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 = version_id_col 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 self.inherits = inherits if local_table is not None: self.local_table = coercions.expect( roles.StrictFromClauseRole, local_table ) else: self.local_table = None self.inherit_condition = inherit_condition self.inherit_foreign_keys = inherit_foreign_keys self._init_properties = properties or {} self._delete_orphans = [] self.batch = batch self.eager_defaults = eager_defaults self.column_prefix = column_prefix self.polymorphic_on = ( coercions.expect( roles.ColumnArgumentOrKeyRole, polymorphic_on, argname="polymorphic_on", ) if polymorphic_on is not None else None ) 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: 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() # major attributes initialized at the classlevel so that # they can be Sphinx-documented. is_mapper = True """Part of the inspection API.""" represents_outer_join = False @property def mapper(self): """Part of the inspection API. Returns self. """ return self def _gen_cache_key(self, anon_map, bindparams): return (self,) @property def entity(self): r"""Part of the inspection API. Returns self.class\_. """ return self.class_ local_table = None """The :class:`_expression.Selectable` which this :class:`_orm.Mapper` manages. Typically is an instance of :class:`_schema.Table` or :class:`_expression.Alias`. May also be ``None``. 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, the local table is the same as the "mapped" table. For joined-table inheritance mappers, local_table will be the particular sub-table of the overall "join" which this :class:`_orm.Mapper` represents. If this mapper is a single-table inheriting mapper, local_table will be ``None``. .. seealso:: :attr:`_orm.Mapper.persist_selectable`. """ persist_selectable = None """The :class:`_expression.Selectable` to which this :class:`_orm.Mapper` is mapped. Typically an instance of :class:`_schema.Table`, :class:`_expression.Join`, or :class:`_expression.Alias`. The :attr:`_orm.Mapper.persist_selectable` is separate from :attr:`_orm.Mapper.selectable` in that the former represents columns that are mapped on this class or its superclasses, whereas the latter may be a "polymorphic" selectable that contains additional columns which are in fact mapped on subclasses only. "persist selectable" is the "thing the mapper writes to" and "selectable" is the "thing the mapper selects from". :attr:`_orm.Mapper.persist_selectable` is also separate from :attr:`_orm.Mapper.local_table`, which represents the set of columns that are locally mapped on this class directly. .. seealso:: :attr:`_orm.Mapper.selectable`. :attr:`_orm.Mapper.local_table`. """ inherits = None """References the :class:`_orm.Mapper` which this :class:`_orm.Mapper` inherits from, if any. This is a *read only* attribute determined during mapper construction. Behavior is undefined if directly modified. """ configured = 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 = None """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. """ tables = None """An iterable containing the collection of :class:`_schema.Table` 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. """ primary_key = None """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_ = None """The Python class which this :class:`_orm.Mapper` maps. This is a *read only* attribute determined during mapper construction. Behavior is undefined if directly modified. """ class_manager = None """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 = None """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 = None """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 = None """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 = None """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 = None """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 = None """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 = None """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. """ validators = None """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. """ c = None """A synonym for :attr:`_orm.Mapper.columns`.""" @property @util.deprecated("1.3", "Use .persist_selectable") def mapped_table(self): return self.persist_selectable @util.memoized_property def _path_registry(self): 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 isinstance(self.inherits, type): self.inherits = class_mapper(self.inherits, configure=False) 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) ) # inherit_condition is optional. if self.local_table is None: self.local_table = self.inherits.local_table self.persist_selectable = self.inherits.persist_selectable self.single = True 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 util.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, ) ), replace_context=nfe, ) except sa_exc.AmbiguousForeignKeysError as afe: assert self.inherits.local_table is not None assert self.local_table is not None util.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, ) ), replace_context=afe, ) 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 self.inherits.base_mapper.polymorphic_on is not None: util.warn( "Mapper %s does not indicate a polymorphic_identity, " "yet is part of an inheritance hierarchy that has a " "polymorphic_on column of '%s'. Objects of this type " "cannot be loaded polymorphically which can lead to " "degraded or incorrect loading behavior in some " "scenarios. Please establish a polmorphic_identity " "for this class, or leave it un-mapped. " "To omit mapping an intermediary class when using " "declarative, set the '__abstract__ = True' " "attribute on that class." % (self, self.inherits.base_mapper.polymorphic_on) ) 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 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): if with_polymorphic == "*": self.with_polymorphic = ("*", None) elif isinstance(with_polymorphic, (tuple, list)): if isinstance( with_polymorphic[0], util.string_types + (tuple, list) ): self.with_polymorphic = with_polymorphic else: self.with_polymorphic = (with_polymorphic, None) elif with_polymorphic is not None: raise sa_exc.ArgumentError("Invalid setting for with_polymorphic") 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] != "*": 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, # we will emit a deprecation warning below when we also see that # it has no registry. manager = attributes.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 self.registry = manager.registry self._identity_class = manager.mapper._identity_class manager.registry._add_non_primary_mapper(self) return if manager is not None: assert manager.class_ is self.class_ if manager.is_mapped: # changed in #7579: # this message is defined in two places as of this change, # also in decl_api -> _add_manager(). in 2.0, this codepath # is removed as any calls to mapper() / Mapper without # the registry setting up first will be rejected. raise sa_exc.ArgumentError( "Class '%s' already has a primary mapper defined. " % self.class_ ) # else: # a ClassManager may already exist as # ClassManager.instrument_attribute() creates # new managers for each subclass if they don't yet exist. 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, ) if not manager.registry: util.warn_deprecated_20( "Calling the mapper() function directly outside of a " "declarative registry is deprecated." " Please use the sqlalchemy.orm.registry.map_imperatively() " "function for a classical mapping." ) assert _legacy_registry is not None _legacy_registry._add_manager(manager) self.class_manager = manager 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): self.configured = True self._ready_for_configure = True self._dispose_called = True self.__dict__.pop("_configure_failed", None) def _configure_pks(self): self.tables = sql_util.find_tables(self.persist_selectable) 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. tables = set(self.tables + [self.persist_selectable]) self._all_tables.update(tables) for t in tables: if t.primary_key and pk_cols.issuperset(t.primary_key): # ordering is important since it determines the ordering of # mapper.primary_key (and therefore query.get()) self._pks_by_table[t] = util.ordered_column_set( t.primary_key ).intersection(pk_cols) self._cols_by_table[t] = util.ordered_column_set(t.c).intersection( all_cols ) # if explicit PK argument sent, add those columns to the # primary key mappings if self._primary_key_argument: for k in self._primary_key_argument: 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 if self._primary_key_argument: primary_key = [ self.persist_selectable.corresponding_column(c) for c in self._primary_key_argument ] 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 = set( 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): # TODO: consider using DedupeColumnCollection self.columns = self.c = sql_base.ColumnCollection() # object attribute names mapped to MapperProperty objects self._props = util.OrderedDict() # table columns mapped to MapperProperty self._columntoproperty = _ColumnMapping(self) # load custom properties if self._init_properties: for key, prop in self._init_properties.items(): self._configure_property(key, prop, False) # pull properties from the inherited mapper if any. if self.inherits: for key, prop in self.inherits._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) # create properties for each column in the mapped table, # for those columns which don't already map to a property for column in self.persist_selectable.columns: if 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 if self.polymorphic_on is not None: setter = True if isinstance(self.polymorphic_on, util.string_types): # polymorphic_on specified as a string - link # it to mapped ColumnProperty try: self.polymorphic_on = self._props[self.polymorphic_on] except KeyError as err: util.raise_( sa_exc.ArgumentError( "Can't determine polymorphic_on " "value '%s' - no attribute is " "mapped to this name." % self.polymorphic_on ), replace_context=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].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(col.key, col.key, False, col): raise sa_exc.InvalidRequestError( "Cannot exclude or override the " "discriminator column %r" % col.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._validate_polymorphic_identity = ( mapper._validate_polymorphic_identity ) else: self._set_polymorphic_identity = None return if setter: def _set_polymorphic_identity(state): dict_ = state.dict state.get_impl(polymorphic_key).set( state, dict_, state.manager.mapper.polymorphic_identity, None, ) 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._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, prop, init=True, setparent=True): descriptor_props = util.preloaded.orm_descriptor_props self._log("_configure_property(%s, %s)", key, prop.__class__.__name__) if not isinstance(prop, MapperProperty): prop = self._property_from_column(key, prop) 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 col in col.proxy_set: self._columntoproperty[col] = prop 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) ) if ( key in self._props and not isinstance(prop, properties.ColumnProperty) and not isinstance( self._props[key], ( properties.ColumnProperty, descriptor_props.ConcreteInheritedProperty, ), ) ): util.warn( "Property %s on %s being replaced with new " "property %s; the old property will be discarded" % (self._props[key], self, prop) ) oldprop = self._props[key] self._path_registry.pop(oldprop, None) 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() @util.preload_module("sqlalchemy.orm.descriptor_props") def _property_from_column(self, key, prop): """generate/update a :class:`.ColumnProperty` given a :class:`_schema.Column` object.""" descriptor_props = util.preloaded.orm_descriptor_props # we were passed a Column or a list of Columns; # generate a properties.ColumnProperty columns = util.to_list(prop) column = columns[0] assert isinstance(column, expression.ColumnElement) prop = self._props.get(key, None) if isinstance(prop, properties.ColumnProperty): if ( ( not self._inherits_equated_pairs or (prop.columns[0], column) not in self._inherits_equated_pairs ) and not prop.columns[0].shares_lineage(column) and prop.columns[0] is not self.version_id_col and column is not self.version_id_col ): warn_only = prop.parent is not self msg = ( "Implicitly combining column %s with column " "%s under attribute '%s'. Please configure one " "or more attributes for these same-named columns " "explicitly." % (prop.columns[-1], 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 prop = prop.copy() prop.columns.insert(0, column) self._log( "inserting column to existing list " "in properties.ColumnProperty %s" % (key) ) return prop elif prop is None or isinstance( prop, descriptor_props.ConcreteInheritedProperty ): 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) 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) ) def _check_configure(self): if self.registry._new_mappers: _configure_registries({self.registry}, cascade=True) def _post_configure_properties(self): """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, prop): """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. """ self._init_properties[key] = prop self._configure_property(key, prop, init=self.configured) def _expire_memoizations(self): for mapper in self.iterate_to_root(): mapper._reset_memoizations() @property def _log_desc(self): 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, *args): self.logger.info("%s " + msg, *((self._log_desc,) + args)) def _log_debug(self, msg, *args): self.logger.debug("%s " + msg, *((self._log_desc,) + args)) def __repr__(self): return "<Mapper at 0x%x; %s>" % (id(self), self.class_.__name__) def __str__(self): return "mapped class %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): 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): return key in self._props def get_property(self, key, _configure_mappers=True): """return a MapperProperty associated with the given key.""" if _configure_mappers: self._check_configure() try: return self._props[key] except KeyError as err: util.raise_( sa_exc.InvalidRequestError( "Mapper '%s' has no property '%s'" % (self, key) ), replace_context=err, ) def get_property_by_column(self, column): """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.""" self._check_configure() return iter(self._props.values()) def _mappers_from_spec(self, spec, selectable): """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: mappers = 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: mappers.update(m.iterate_to_root()) else: mappers.add(m) mappers = [m for m in self.self_and_descendants if m in mappers] 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, innerjoin): """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 _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) else: return None @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. # # 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. return ( self.with_polymorphic or self._requires_row_aliasing or self.base_mapper.with_polymorphic or self.base_mapper._requires_row_aliasing ) @HasMemoized.memoized_attribute def _with_polymorphic_mappers(self): 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.memoized_attribute def _with_polymorphic_selectable(self): 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.memoized_attribute def _insert_cols_evaluating_none(self): return dict( ( 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 dict( ( 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 dict( ( table, dict( (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 dict( (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 dict( ( 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): return dict( ( table, frozenset( [ col.key for col in columns if col.server_default is not None ] ), ) for table, columns in self._cols_by_table.items() ) @HasMemoized.memoized_attribute def _server_default_plus_onupdate_propkeys(self): result = set() for table, columns in self._cols_by_table.items(): for col in columns: if ( col.server_default is not None or col.server_onupdate is not None ) and col in self._columntoproperty: result.add(self._columntoproperty[col].key) return result @HasMemoized.memoized_attribute def _server_onupdate_default_cols(self): return dict( ( table, frozenset( [ col.key for col in columns if col.server_onupdate is not None ] ), ) for table, columns in self._cols_by_table.items() ) @HasMemoized.memoized_instancemethod def __clause_element__(self): annotations = { "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): """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=None, selectable=False, innerjoin=False ): 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[prop.columns[0]] if adapter else prop.columns[0] for prop in poly_properties if isinstance(prop, properties.ColumnProperty) and prop._renders_in_subqueries ] 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): if self.with_polymorphic: return sql_util.ColumnAdapter( self.selectable, equivalents=self._equivalent_columns ) 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): """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.ImmutableProperties(self._props) @HasMemoized.memoized_attribute def all_orm_descriptors(self): """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.ImmutableProperties( dict(self.class_manager._all_sqla_attributes()) ) @HasMemoized.memoized_attribute @util.preload_module("sqlalchemy.orm.descriptor_props") def _pk_synonyms(self): """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): """Return a namespace of all :class:`.SynonymProperty` 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): """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) @util.preload_module("sqlalchemy.orm.relationships") @HasMemoized.memoized_attribute def relationships(self): """A namespace of all :class:`.RelationshipProperty` 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): """Return a namespace of all :class:`.CompositeProperty` 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_): self._check_configure() return util.ImmutableProperties( 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): """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 = util.column_dict() def visit_binary(binary): if binary.operator == operators.eq: if binary.left in result: result[binary.left].add(binary.right) else: result[binary.left] = util.column_set((binary.right,)) if binary.right in result: result[binary.right].add(binary.left) else: result[binary.right] = util.column_set((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, obj): 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. """ # 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): """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): """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, allow_subtypes): 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): """Return True if the this mapper inherits from the given mapper.""" m = self while m and m is not other: m = m.inherits return bool(m) def iterate_to_root(self): m = self while m: yield m m = m.inherits @HasMemoized.memoized_attribute def self_and_descendants(self): """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): """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): """Return the primary mapper corresponding to this mapper's class key (class).""" return self.class_manager.mapper @property def primary_base_mapper(self): return self.class_manager.mapper.base_mapper def _result_has_identity_key(self, result, adapter=None): pk_cols = 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, identity_token=None, adapter=None): """Return an identity-map key for use in storing/retrieving an item from the identity map. :param row: A :class:`.Row` instance. The columns which are mapped by this :class:`_orm.Mapper` should be locatable in the row, preferably via the :class:`_schema.Column` object directly (as is the case when a :func:`_expression.select` construct is executed), or via string names of the form ``<tablename>_<colname>``. """ pk_cols = self.primary_key if adapter: pk_cols = [adapter.columns[c] for c in pk_cols] return ( self._identity_class, tuple(row[column] for column in pk_cols), identity_token, ) def identity_key_from_primary_key(self, primary_key, identity_token=None): """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): """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, attributes.PASSIVE_OFF) def _identity_key_from_state( self, state, passive=attributes.PASSIVE_RETURN_NO_VALUE ): 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): """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, attributes.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() 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(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, dict_, column, passive=attributes.PASSIVE_RETURN_NO_VALUE ): 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=attributes.PASSIVE_OFF ) def _get_committed_state_attr_by_column( self, state, dict_, column, passive=attributes.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( 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=attributes.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=attributes.PASSIVE_NO_INITIALIZE, ) if rightval in orm_util._none_set: raise _OptGetColumnsNotAvailable() binary.right = sql.bindparam( None, rightval, type_=binary.right.type ) allconds = [] 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: 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: allconds[0] = visitors.cloned_traverse( allconds[0], {}, {"binary": visit_binary} ) except _OptGetColumnsNotAvailable: return None 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 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): """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) for prop in self.attrs: # 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 is self 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.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), ) 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.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}, ) primary_key = [ sql_util._deep_annotate(pk, {"_orm_adapt": True}) for pk in self.primary_key ] 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): return self._subclass_load_via_in(self) def cascade_iterator(self, type_, state, halt_on=None): 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() prp, mpp = object(), object() assert state.mapper.isa(self) 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 type_ not in prop.cascade: continue 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 _sorted_tables(self): table_to_mapper = {} 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, callable_): if key in self._memoized_values: return 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(list) 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( util.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(): """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, cascade): 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() # 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() @util.preload_module("sqlalchemy.orm.decl_api") def _do_configure_registries(registries, cascade): 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 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, cascade): 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, **kw): 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. .. versionadded:: 0.9.0 .. seealso:: :ref:`simple_validators` - usage examples for :func:`.validates` """ include_removes = kw.pop("include_removes", False) include_backrefs = kw.pop("include_backrefs", True) def wrap(fn): fn.__sa_validators__ = names fn.__sa_validation_opts__ = { "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): """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) )