# orm/util.py # Copyright (C) 2005-2023 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php import re import types import weakref from . import attributes # noqa from .base import _class_to_mapper # noqa from .base import _never_set # noqa from .base import _none_set # noqa from .base import attribute_str # noqa from .base import class_mapper # noqa from .base import InspectionAttr # noqa from .base import instance_str # noqa from .base import object_mapper # noqa from .base import object_state # noqa from .base import state_attribute_str # noqa from .base import state_class_str # noqa from .base import state_str # noqa from .interfaces import CriteriaOption from .interfaces import MapperProperty # noqa from .interfaces import ORMColumnsClauseRole from .interfaces import ORMEntityColumnsClauseRole from .interfaces import ORMFromClauseRole from .interfaces import PropComparator # noqa from .path_registry import PathRegistry # noqa from .. import event from .. import exc as sa_exc from .. import inspection from .. import sql from .. import util from ..engine.result import result_tuple from ..sql import base as sql_base from ..sql import coercions from ..sql import expression from ..sql import lambdas from ..sql import roles from ..sql import util as sql_util from ..sql import visitors from ..sql.annotation import SupportsCloneAnnotations from ..sql.base import ColumnCollection all_cascades = frozenset( ( "delete", "delete-orphan", "all", "merge", "expunge", "save-update", "refresh-expire", "none", ) ) class CascadeOptions(frozenset): """Keeps track of the options sent to :paramref:`.relationship.cascade`""" _add_w_all_cascades = all_cascades.difference( ["all", "none", "delete-orphan"] ) _allowed_cascades = all_cascades _viewonly_cascades = ["expunge", "all", "none", "refresh-expire", "merge"] __slots__ = ( "save_update", "delete", "refresh_expire", "merge", "expunge", "delete_orphan", ) def __new__(cls, value_list): if isinstance(value_list, util.string_types) or value_list is None: return cls.from_string(value_list) values = set(value_list) if values.difference(cls._allowed_cascades): raise sa_exc.ArgumentError( "Invalid cascade option(s): %s" % ", ".join( [ repr(x) for x in sorted( values.difference(cls._allowed_cascades) ) ] ) ) if "all" in values: values.update(cls._add_w_all_cascades) if "none" in values: values.clear() values.discard("all") self = frozenset.__new__(CascadeOptions, values) self.save_update = "save-update" in values self.delete = "delete" in values self.refresh_expire = "refresh-expire" in values self.merge = "merge" in values self.expunge = "expunge" in values self.delete_orphan = "delete-orphan" in values if self.delete_orphan and not self.delete: util.warn( "The 'delete-orphan' cascade " "option requires 'delete'." ) return self def __repr__(self): return "CascadeOptions(%r)" % (",".join([x for x in sorted(self)])) @classmethod def from_string(cls, arg): values = [c for c in re.split(r"\s*,\s*", arg or "") if c] return cls(values) def _validator_events(desc, key, validator, include_removes, include_backrefs): """Runs a validation method on an attribute value to be set or appended. """ if not include_backrefs: def detect_is_backref(state, initiator): impl = state.manager[key].impl return initiator.impl is not impl if include_removes: def append(state, value, initiator): if initiator.op is not attributes.OP_BULK_REPLACE and ( include_backrefs or not detect_is_backref(state, initiator) ): return validator(state.obj(), key, value, False) else: return value def bulk_set(state, values, initiator): if include_backrefs or not detect_is_backref(state, initiator): obj = state.obj() values[:] = [ validator(obj, key, value, False) for value in values ] def set_(state, value, oldvalue, initiator): if include_backrefs or not detect_is_backref(state, initiator): return validator(state.obj(), key, value, False) else: return value def remove(state, value, initiator): if include_backrefs or not detect_is_backref(state, initiator): validator(state.obj(), key, value, True) else: def append(state, value, initiator): if initiator.op is not attributes.OP_BULK_REPLACE and ( include_backrefs or not detect_is_backref(state, initiator) ): return validator(state.obj(), key, value) else: return value def bulk_set(state, values, initiator): if include_backrefs or not detect_is_backref(state, initiator): obj = state.obj() values[:] = [validator(obj, key, value) for value in values] def set_(state, value, oldvalue, initiator): if include_backrefs or not detect_is_backref(state, initiator): return validator(state.obj(), key, value) else: return value event.listen(desc, "append", append, raw=True, retval=True) event.listen(desc, "bulk_replace", bulk_set, raw=True) event.listen(desc, "set", set_, raw=True, retval=True) if include_removes: event.listen(desc, "remove", remove, raw=True, retval=True) def polymorphic_union( table_map, typecolname, aliasname="p_union", cast_nulls=True ): """Create a ``UNION`` statement used by a polymorphic mapper. See :ref:`concrete_inheritance` for an example of how this is used. :param table_map: mapping of polymorphic identities to :class:`_schema.Table` objects. :param typecolname: string name of a "discriminator" column, which will be derived from the query, producing the polymorphic identity for each row. If ``None``, no polymorphic discriminator is generated. :param aliasname: name of the :func:`~sqlalchemy.sql.expression.alias()` construct generated. :param cast_nulls: if True, non-existent columns, which are represented as labeled NULLs, will be passed into CAST. This is a legacy behavior that is problematic on some backends such as Oracle - in which case it can be set to False. """ colnames = util.OrderedSet() colnamemaps = {} types = {} for key in table_map: table = table_map[key] table = coercions.expect( roles.StrictFromClauseRole, table, allow_select=True ) table_map[key] = table m = {} for c in table.c: if c.key == typecolname: raise sa_exc.InvalidRequestError( "Polymorphic union can't use '%s' as the discriminator " "column due to mapped column %r; please apply the " "'typecolname' " "argument; this is available on " "ConcreteBase as '_concrete_discriminator_name'" % (typecolname, c) ) colnames.add(c.key) m[c.key] = c types[c.key] = c.type colnamemaps[table] = m def col(name, table): try: return colnamemaps[table][name] except KeyError: if cast_nulls: return sql.cast(sql.null(), types[name]).label(name) else: return sql.type_coerce(sql.null(), types[name]).label(name) result = [] for type_, table in table_map.items(): if typecolname is not None: result.append( sql.select( *( [col(name, table) for name in colnames] + [ sql.literal_column( sql_util._quote_ddl_expr(type_) ).label(typecolname) ] ) ).select_from(table) ) else: result.append( sql.select( *[col(name, table) for name in colnames] ).select_from(table) ) return sql.union_all(*result).alias(aliasname) def identity_key(*args, **kwargs): r"""Generate "identity key" tuples, as are used as keys in the :attr:`.Session.identity_map` dictionary. This function has several call styles: * ``identity_key(class, ident, identity_token=token)`` This form receives a mapped class and a primary key scalar or tuple as an argument. E.g.:: >>> identity_key(MyClass, (1, 2)) (, (1, 2), None) :param class: mapped class (must be a positional argument) :param ident: primary key, may be a scalar or tuple argument. :param identity_token: optional identity token .. versionadded:: 1.2 added identity_token * ``identity_key(instance=instance)`` This form will produce the identity key for a given instance. The instance need not be persistent, only that its primary key attributes are populated (else the key will contain ``None`` for those missing values). E.g.:: >>> instance = MyClass(1, 2) >>> identity_key(instance=instance) (, (1, 2), None) In this form, the given instance is ultimately run though :meth:`_orm.Mapper.identity_key_from_instance`, which will have the effect of performing a database check for the corresponding row if the object is expired. :param instance: object instance (must be given as a keyword arg) * ``identity_key(class, row=row, identity_token=token)`` This form is similar to the class/tuple form, except is passed a database result row as a :class:`.Row` object. E.g.:: >>> row = engine.execute(\ text("select * from table where a=1 and b=2")\ ).first() >>> identity_key(MyClass, row=row) (, (1, 2), None) :param class: mapped class (must be a positional argument) :param row: :class:`.Row` row returned by a :class:`_engine.CursorResult` (must be given as a keyword arg) :param identity_token: optional identity token .. versionadded:: 1.2 added identity_token """ if args: row = None largs = len(args) if largs == 1: class_ = args[0] try: row = kwargs.pop("row") except KeyError: ident = kwargs.pop("ident") elif largs in (2, 3): class_, ident = args else: raise sa_exc.ArgumentError( "expected up to three positional arguments, " "got %s" % largs ) identity_token = kwargs.pop("identity_token", None) if kwargs: raise sa_exc.ArgumentError( "unknown keyword arguments: %s" % ", ".join(kwargs) ) mapper = class_mapper(class_) if row is None: return mapper.identity_key_from_primary_key( util.to_list(ident), identity_token=identity_token ) else: return mapper.identity_key_from_row( row, identity_token=identity_token ) else: instance = kwargs.pop("instance") if kwargs: raise sa_exc.ArgumentError( "unknown keyword arguments: %s" % ", ".join(kwargs.keys) ) mapper = object_mapper(instance) return mapper.identity_key_from_instance(instance) class ORMAdapter(sql_util.ColumnAdapter): """ColumnAdapter subclass which excludes adaptation of entities from non-matching mappers. """ def __init__( self, entity, equivalents=None, adapt_required=False, allow_label_resolve=True, anonymize_labels=False, ): info = inspection.inspect(entity) self.mapper = info.mapper selectable = info.selectable is_aliased_class = info.is_aliased_class if is_aliased_class: self.aliased_class = entity else: self.aliased_class = None sql_util.ColumnAdapter.__init__( self, selectable, equivalents, adapt_required=adapt_required, allow_label_resolve=allow_label_resolve, anonymize_labels=anonymize_labels, include_fn=self._include_fn, ) def _include_fn(self, elem): entity = elem._annotations.get("parentmapper", None) return not entity or entity.isa(self.mapper) or self.mapper.isa(entity) class AliasedClass(object): r"""Represents an "aliased" form of a mapped class for usage with Query. The ORM equivalent of a :func:`~sqlalchemy.sql.expression.alias` construct, this object mimics the mapped class using a ``__getattr__`` scheme and maintains a reference to a real :class:`~sqlalchemy.sql.expression.Alias` object. A primary purpose of :class:`.AliasedClass` is to serve as an alternate within a SQL statement generated by the ORM, such that an existing mapped entity can be used in multiple contexts. A simple example:: # find all pairs of users with the same name user_alias = aliased(User) session.query(User, user_alias).\ join((user_alias, User.id > user_alias.id)).\ filter(User.name == user_alias.name) :class:`.AliasedClass` is also capable of mapping an existing mapped class to an entirely new selectable, provided this selectable is column- compatible with the existing mapped selectable, and it can also be configured in a mapping as the target of a :func:`_orm.relationship`. See the links below for examples. The :class:`.AliasedClass` object is constructed typically using the :func:`_orm.aliased` function. It also is produced with additional configuration when using the :func:`_orm.with_polymorphic` function. The resulting object is an instance of :class:`.AliasedClass`. This object implements an attribute scheme which produces the same attribute and method interface as the original mapped class, allowing :class:`.AliasedClass` to be compatible with any attribute technique which works on the original class, including hybrid attributes (see :ref:`hybrids_toplevel`). The :class:`.AliasedClass` can be inspected for its underlying :class:`_orm.Mapper`, aliased selectable, and other information using :func:`_sa.inspect`:: from sqlalchemy import inspect my_alias = aliased(MyClass) insp = inspect(my_alias) The resulting inspection object is an instance of :class:`.AliasedInsp`. .. seealso:: :func:`.aliased` :func:`.with_polymorphic` :ref:`relationship_aliased_class` :ref:`relationship_to_window_function` """ def __init__( self, mapped_class_or_ac, alias=None, name=None, flat=False, adapt_on_names=False, # TODO: None for default here? with_polymorphic_mappers=(), with_polymorphic_discriminator=None, base_alias=None, use_mapper_path=False, represents_outer_join=False, ): insp = inspection.inspect(mapped_class_or_ac) mapper = insp.mapper nest_adapters = False if alias is None: if insp.is_aliased_class and insp.selectable._is_subquery: alias = insp.selectable.alias() else: alias = ( mapper._with_polymorphic_selectable._anonymous_fromclause( name=name, flat=flat, ) ) elif insp.is_aliased_class: nest_adapters = True self._aliased_insp = AliasedInsp( self, insp, alias, name, with_polymorphic_mappers if with_polymorphic_mappers else mapper.with_polymorphic_mappers, with_polymorphic_discriminator if with_polymorphic_discriminator is not None else mapper.polymorphic_on, base_alias, use_mapper_path, adapt_on_names, represents_outer_join, nest_adapters, ) self.__name__ = "AliasedClass_%s" % mapper.class_.__name__ @classmethod def _reconstitute_from_aliased_insp(cls, aliased_insp): obj = cls.__new__(cls) obj.__name__ = "AliasedClass_%s" % aliased_insp.mapper.class_.__name__ obj._aliased_insp = aliased_insp if aliased_insp._is_with_polymorphic: for sub_aliased_insp in aliased_insp._with_polymorphic_entities: if sub_aliased_insp is not aliased_insp: ent = AliasedClass._reconstitute_from_aliased_insp( sub_aliased_insp ) setattr(obj, sub_aliased_insp.class_.__name__, ent) return obj def __getattr__(self, key): try: _aliased_insp = self.__dict__["_aliased_insp"] except KeyError: raise AttributeError() else: target = _aliased_insp._target # maintain all getattr mechanics attr = getattr(target, key) # attribute is a method, that will be invoked against a # "self"; so just return a new method with the same function and # new self if hasattr(attr, "__call__") and hasattr(attr, "__self__"): return types.MethodType(attr.__func__, self) # attribute is a descriptor, that will be invoked against a # "self"; so invoke the descriptor against this self if hasattr(attr, "__get__"): attr = attr.__get__(None, self) # attributes within the QueryableAttribute system will want this # to be invoked so the object can be adapted if hasattr(attr, "adapt_to_entity"): attr = attr.adapt_to_entity(_aliased_insp) setattr(self, key, attr) return attr def _get_from_serialized(self, key, mapped_class, aliased_insp): # this method is only used in terms of the # sqlalchemy.ext.serializer extension attr = getattr(mapped_class, key) if hasattr(attr, "__call__") and hasattr(attr, "__self__"): return types.MethodType(attr.__func__, self) # attribute is a descriptor, that will be invoked against a # "self"; so invoke the descriptor against this self if hasattr(attr, "__get__"): attr = attr.__get__(None, self) # attributes within the QueryableAttribute system will want this # to be invoked so the object can be adapted if hasattr(attr, "adapt_to_entity"): aliased_insp._weak_entity = weakref.ref(self) attr = attr.adapt_to_entity(aliased_insp) setattr(self, key, attr) return attr def __repr__(self): return "" % ( id(self), self._aliased_insp._target.__name__, ) def __str__(self): return str(self._aliased_insp) class AliasedInsp( ORMEntityColumnsClauseRole, ORMFromClauseRole, sql_base.MemoizedHasCacheKey, InspectionAttr, ): """Provide an inspection interface for an :class:`.AliasedClass` object. The :class:`.AliasedInsp` object is returned given an :class:`.AliasedClass` using the :func:`_sa.inspect` function:: from sqlalchemy import inspect from sqlalchemy.orm import aliased my_alias = aliased(MyMappedClass) insp = inspect(my_alias) Attributes on :class:`.AliasedInsp` include: * ``entity`` - the :class:`.AliasedClass` represented. * ``mapper`` - the :class:`_orm.Mapper` mapping the underlying class. * ``selectable`` - the :class:`_expression.Alias` construct which ultimately represents an aliased :class:`_schema.Table` or :class:`_expression.Select` construct. * ``name`` - the name of the alias. Also is used as the attribute name when returned in a result tuple from :class:`_query.Query`. * ``with_polymorphic_mappers`` - collection of :class:`_orm.Mapper` objects indicating all those mappers expressed in the select construct for the :class:`.AliasedClass`. * ``polymorphic_on`` - an alternate column or SQL expression which will be used as the "discriminator" for a polymorphic load. .. seealso:: :ref:`inspection_toplevel` """ _cache_key_traversal = [ ("name", visitors.ExtendedInternalTraversal.dp_string), ("_adapt_on_names", visitors.ExtendedInternalTraversal.dp_boolean), ("_use_mapper_path", visitors.ExtendedInternalTraversal.dp_boolean), ("_target", visitors.ExtendedInternalTraversal.dp_inspectable), ("selectable", visitors.ExtendedInternalTraversal.dp_clauseelement), ( "with_polymorphic_mappers", visitors.InternalTraversal.dp_has_cache_key_list, ), ("polymorphic_on", visitors.InternalTraversal.dp_clauseelement), ] def __init__( self, entity, inspected, selectable, name, with_polymorphic_mappers, polymorphic_on, _base_alias, _use_mapper_path, adapt_on_names, represents_outer_join, nest_adapters, ): mapped_class_or_ac = inspected.entity mapper = inspected.mapper self._weak_entity = weakref.ref(entity) self.mapper = mapper self.selectable = ( self.persist_selectable ) = self.local_table = selectable self.name = name self.polymorphic_on = polymorphic_on self._base_alias = weakref.ref(_base_alias or self) self._use_mapper_path = _use_mapper_path self.represents_outer_join = represents_outer_join self._nest_adapters = nest_adapters if with_polymorphic_mappers: self._is_with_polymorphic = True self.with_polymorphic_mappers = with_polymorphic_mappers self._with_polymorphic_entities = [] for poly in self.with_polymorphic_mappers: if poly is not mapper: ent = AliasedClass( poly.class_, selectable, base_alias=self, adapt_on_names=adapt_on_names, use_mapper_path=_use_mapper_path, ) setattr(self.entity, poly.class_.__name__, ent) self._with_polymorphic_entities.append(ent._aliased_insp) else: self._is_with_polymorphic = False self.with_polymorphic_mappers = [mapper] self._adapter = sql_util.ColumnAdapter( selectable, equivalents=mapper._equivalent_columns, adapt_on_names=adapt_on_names, anonymize_labels=True, # make sure the adapter doesn't try to grab other tables that # are not even the thing we are mapping, such as embedded # selectables in subqueries or CTEs. See issue #6060 adapt_from_selectables={ m.selectable for m in self.with_polymorphic_mappers if not adapt_on_names }, ) if nest_adapters: self._adapter = inspected._adapter.wrap(self._adapter) self._adapt_on_names = adapt_on_names self._target = mapped_class_or_ac # self._target = mapper.class_ # mapped_class_or_ac @property def entity(self): # to eliminate reference cycles, the AliasedClass is held weakly. # this produces some situations where the AliasedClass gets lost, # particularly when one is created internally and only the AliasedInsp # is passed around. # to work around this case, we just generate a new one when we need # it, as it is a simple class with very little initial state on it. ent = self._weak_entity() if ent is None: ent = AliasedClass._reconstitute_from_aliased_insp(self) self._weak_entity = weakref.ref(ent) return ent is_aliased_class = True "always returns True" @util.memoized_instancemethod def __clause_element__(self): return self.selectable._annotate( { "parentmapper": self.mapper, "parententity": self, "entity_namespace": self, } )._set_propagate_attrs( {"compile_state_plugin": "orm", "plugin_subject": self} ) @property def entity_namespace(self): return self.entity @property def class_(self): """Return the mapped class ultimately represented by this :class:`.AliasedInsp`.""" return self.mapper.class_ @property def _path_registry(self): if self._use_mapper_path: return self.mapper._path_registry else: return PathRegistry.per_mapper(self) def __getstate__(self): return { "entity": self.entity, "mapper": self.mapper, "alias": self.selectable, "name": self.name, "adapt_on_names": self._adapt_on_names, "with_polymorphic_mappers": self.with_polymorphic_mappers, "with_polymorphic_discriminator": self.polymorphic_on, "base_alias": self._base_alias(), "use_mapper_path": self._use_mapper_path, "represents_outer_join": self.represents_outer_join, "nest_adapters": self._nest_adapters, } def __setstate__(self, state): self.__init__( state["entity"], state["mapper"], state["alias"], state["name"], state["with_polymorphic_mappers"], state["with_polymorphic_discriminator"], state["base_alias"], state["use_mapper_path"], state["adapt_on_names"], state["represents_outer_join"], state["nest_adapters"], ) def _adapt_element(self, elem, key=None): d = { "parententity": self, "parentmapper": self.mapper, } if key: d["proxy_key"] = key return ( self._adapter.traverse(elem) ._annotate(d) ._set_propagate_attrs( {"compile_state_plugin": "orm", "plugin_subject": self} ) ) def _entity_for_mapper(self, mapper): self_poly = self.with_polymorphic_mappers if mapper in self_poly: if mapper is self.mapper: return self else: return getattr( self.entity, mapper.class_.__name__ )._aliased_insp elif mapper.isa(self.mapper): return self else: assert False, "mapper %s doesn't correspond to %s" % (mapper, self) @util.memoized_property def _get_clause(self): onclause, replacemap = self.mapper._get_clause return ( self._adapter.traverse(onclause), { self._adapter.traverse(col): param for col, param in replacemap.items() }, ) @util.memoized_property def _memoized_values(self): return {} @util.memoized_property def _all_column_expressions(self): if self._is_with_polymorphic: cols_plus_keys = self.mapper._columns_plus_keys( [ent.mapper for ent in self._with_polymorphic_entities] ) else: cols_plus_keys = self.mapper._columns_plus_keys() cols_plus_keys = [ (key, self._adapt_element(col)) for key, col in cols_plus_keys ] return ColumnCollection(cols_plus_keys) def _memo(self, key, callable_, *args, **kw): if key in self._memoized_values: return self._memoized_values[key] else: self._memoized_values[key] = value = callable_(*args, **kw) return value def __repr__(self): if self.with_polymorphic_mappers: with_poly = "(%s)" % ", ".join( mp.class_.__name__ for mp in self.with_polymorphic_mappers ) else: with_poly = "" return "" % ( id(self), self.class_.__name__, with_poly, ) def __str__(self): if self._is_with_polymorphic: return "with_polymorphic(%s, [%s])" % ( self._target.__name__, ", ".join( mp.class_.__name__ for mp in self.with_polymorphic_mappers if mp is not self.mapper ), ) else: return "aliased(%s)" % (self._target.__name__,) class _WrapUserEntity(object): """A wrapper used within the loader_criteria lambda caller so that we can bypass declared_attr descriptors on unmapped mixins, which normally emit a warning for such use. might also be useful for other per-lambda instrumentations should the need arise. """ __slots__ = ("subject",) def __init__(self, subject): self.subject = subject @util.preload_module("sqlalchemy.orm.decl_api") def __getattribute__(self, name): decl_api = util.preloaded.orm.decl_api subject = object.__getattribute__(self, "subject") if name in subject.__dict__ and isinstance( subject.__dict__[name], decl_api.declared_attr ): return subject.__dict__[name].fget(subject) else: return getattr(subject, name) class LoaderCriteriaOption(CriteriaOption): """Add additional WHERE criteria to the load for all occurrences of a particular entity. :class:`_orm.LoaderCriteriaOption` is invoked using the :func:`_orm.with_loader_criteria` function; see that function for details. .. versionadded:: 1.4 """ _traverse_internals = [ ("root_entity", visitors.ExtendedInternalTraversal.dp_plain_obj), ("entity", visitors.ExtendedInternalTraversal.dp_has_cache_key), ("where_criteria", visitors.InternalTraversal.dp_clauseelement), ("include_aliases", visitors.InternalTraversal.dp_boolean), ("propagate_to_loaders", visitors.InternalTraversal.dp_boolean), ] def __init__( self, entity_or_base, where_criteria, loader_only=False, include_aliases=False, propagate_to_loaders=True, track_closure_variables=True, ): """Add additional WHERE criteria to the load for all occurrences of a particular entity. .. versionadded:: 1.4 The :func:`_orm.with_loader_criteria` option is intended to add limiting criteria to a particular kind of entity in a query, **globally**, meaning it will apply to the entity as it appears in the SELECT query as well as within any subqueries, join conditions, and relationship loads, including both eager and lazy loaders, without the need for it to be specified in any particular part of the query. The rendering logic uses the same system used by single table inheritance to ensure a certain discriminator is applied to a table. E.g., using :term:`2.0-style` queries, we can limit the way the ``User.addresses`` collection is loaded, regardless of the kind of loading used:: from sqlalchemy.orm import with_loader_criteria stmt = select(User).options( selectinload(User.addresses), with_loader_criteria(Address, Address.email_address != 'foo')) ) Above, the "selectinload" for ``User.addresses`` will apply the given filtering criteria to the WHERE clause. Another example, where the filtering will be applied to the ON clause of the join, in this example using :term:`1.x style` queries:: q = session.query(User).outerjoin(User.addresses).options( with_loader_criteria(Address, Address.email_address != 'foo')) ) The primary purpose of :func:`_orm.with_loader_criteria` is to use it in the :meth:`_orm.SessionEvents.do_orm_execute` event handler to ensure that all occurrences of a particular entity are filtered in a certain way, such as filtering for access control roles. It also can be used to apply criteria to relationship loads. In the example below, we can apply a certain set of rules to all queries emitted by a particular :class:`_orm.Session`:: session = Session(bind=engine) @event.listens_for("do_orm_execute", session) def _add_filtering_criteria(execute_state): if ( execute_state.is_select and not execute_state.is_column_load and not execute_state.is_relationship_load ): execute_state.statement = execute_state.statement.options( with_loader_criteria( SecurityRole, lambda cls: cls.role.in_(['some_role']), include_aliases=True ) ) In the above example, the :meth:`_orm.SessionEvents.do_orm_execute` event will intercept all queries emitted using the :class:`_orm.Session`. For those queries which are SELECT statements and are not attribute or relationship loads a custom :func:`_orm.with_loader_criteria` option is added to the query. The :func:`_orm.with_loader_criteria` option will be used in the given statement and will also be automatically propagated to all relationship loads that descend from this query. The criteria argument given is a ``lambda`` that accepts a ``cls`` argument. The given class will expand to include all mapped subclass and need not itself be a mapped class. .. tip:: When using :func:`_orm.with_loader_criteria` option in conjunction with the :func:`_orm.contains_eager` loader option, it's important to note that :func:`_orm.with_loader_criteria` only affects the part of the query that determines what SQL is rendered in terms of the WHERE and FROM clauses. The :func:`_orm.contains_eager` option does not affect the rendering of the SELECT statement outside of the columns clause, so does not have any interaction with the :func:`_orm.with_loader_criteria` option. However, the way things "work" is that :func:`_orm.contains_eager` is meant to be used with a query that is already selecting from the additional entities in some way, where :func:`_orm.with_loader_criteria` can apply it's additional criteria. In the example below, assuming a mapping relationship as ``A -> A.bs -> B``, the given :func:`_orm.with_loader_criteria` option will affect the way in which the JOIN is rendered:: stmt = select(A).join(A.bs).options( contains_eager(A.bs), with_loader_criteria(B, B.flag == 1) ) Above, the given :func:`_orm.with_loader_criteria` option will affect the ON clause of the JOIN that is specified by ``.join(A.bs)``, so is applied as expected. The :func:`_orm.contains_eager` option has the effect that columns from ``B`` are added to the columns clause:: SELECT b.id, b.a_id, b.data, b.flag, a.id AS id_1, a.data AS data_1 FROM a JOIN b ON a.id = b.a_id AND b.flag = :flag_1 The use of the :func:`_orm.contains_eager` option within the above statement has no effect on the behavior of the :func:`_orm.with_loader_criteria` option. If the :func:`_orm.contains_eager` option were omitted, the SQL would be the same as regards the FROM and WHERE clauses, where :func:`_orm.with_loader_criteria` continues to add its criteria to the ON clause of the JOIN. The addition of :func:`_orm.contains_eager` only affects the columns clause, in that additional columns against ``b`` are added which are then consumed by the ORM to produce ``B`` instances. .. warning:: The use of a lambda inside of the call to :func:`_orm.with_loader_criteria` is only invoked **once per unique class**. Custom functions should not be invoked within this lambda. See :ref:`engine_lambda_caching` for an overview of the "lambda SQL" feature, which is for advanced use only. :param entity_or_base: a mapped class, or a class that is a super class of a particular set of mapped classes, to which the rule will apply. :param where_criteria: a Core SQL expression that applies limiting criteria. This may also be a "lambda:" or Python function that accepts a target class as an argument, when the given class is a base with many different mapped subclasses. .. note:: To support pickling, use a module-level Python function to produce the SQL expression instead of a lambda or a fixed SQL expression, which tend to not be picklable. :param include_aliases: if True, apply the rule to :func:`_orm.aliased` constructs as well. :param propagate_to_loaders: defaults to True, apply to relationship loaders such as lazy loaders. This indicates that the option object itself including SQL expression is carried along with each loaded instance. Set to ``False`` to prevent the object from being assigned to individual instances. .. seealso:: :ref:`examples_session_orm_events` - includes examples of using :func:`_orm.with_loader_criteria`. :ref:`do_orm_execute_global_criteria` - basic example on how to combine :func:`_orm.with_loader_criteria` with the :meth:`_orm.SessionEvents.do_orm_execute` event. :param track_closure_variables: when False, closure variables inside of a lambda expression will not be used as part of any cache key. This allows more complex expressions to be used inside of a lambda expression but requires that the lambda ensures it returns the identical SQL every time given a particular class. .. versionadded:: 1.4.0b2 """ entity = inspection.inspect(entity_or_base, False) if entity is None: self.root_entity = entity_or_base self.entity = None else: self.root_entity = None self.entity = entity self._where_crit_orig = where_criteria if callable(where_criteria): self.deferred_where_criteria = True self.where_criteria = lambdas.DeferredLambdaElement( where_criteria, roles.WhereHavingRole, lambda_args=( _WrapUserEntity( self.root_entity if self.root_entity is not None else self.entity.entity, ), ), opts=lambdas.LambdaOptions( track_closure_variables=track_closure_variables ), ) else: self.deferred_where_criteria = False self.where_criteria = coercions.expect( roles.WhereHavingRole, where_criteria ) self.include_aliases = include_aliases self.propagate_to_loaders = propagate_to_loaders @classmethod def _unreduce( cls, entity, where_criteria, include_aliases, propagate_to_loaders ): return LoaderCriteriaOption( entity, where_criteria, include_aliases=include_aliases, propagate_to_loaders=propagate_to_loaders, ) def __reduce__(self): return ( LoaderCriteriaOption._unreduce, ( self.entity.class_ if self.entity else self.root_entity, self._where_crit_orig, self.include_aliases, self.propagate_to_loaders, ), ) def _all_mappers(self): if self.entity: for ent in self.entity.mapper.self_and_descendants: yield ent else: stack = list(self.root_entity.__subclasses__()) while stack: subclass = stack.pop(0) ent = inspection.inspect(subclass, raiseerr=False) if ent: for mp in ent.mapper.self_and_descendants: yield mp else: stack.extend(subclass.__subclasses__()) def _should_include(self, compile_state): if ( compile_state.select_statement._annotations.get( "for_loader_criteria", None ) is self ): return False return True def _resolve_where_criteria(self, ext_info): if self.deferred_where_criteria: crit = self.where_criteria._resolve_with_args(ext_info.entity) else: crit = self.where_criteria return sql_util._deep_annotate( crit, {"for_loader_criteria": self}, detect_subquery_cols=True ) def process_compile_state_replaced_entities( self, compile_state, mapper_entities ): return self.process_compile_state(compile_state) def process_compile_state(self, compile_state): """Apply a modification to a given :class:`.CompileState`.""" # if options to limit the criteria to immediate query only, # use compile_state.attributes instead if compile_state.compile_options._with_polymorphic_adapt_map: util.warn( "The with_loader_criteria() function may not work " "correctly with the legacy Query.with_polymorphic() feature. " "Please migrate code to use the with_polymorphic() standalone " "function before using with_loader_criteria()." ) self.get_global_criteria(compile_state.global_attributes) def get_global_criteria(self, attributes): for mp in self._all_mappers(): load_criteria = attributes.setdefault( ("additional_entity_criteria", mp), [] ) load_criteria.append(self) inspection._inspects(AliasedClass)(lambda target: target._aliased_insp) inspection._inspects(AliasedInsp)(lambda target: target) def aliased(element, alias=None, name=None, flat=False, adapt_on_names=False): """Produce an alias of the given element, usually an :class:`.AliasedClass` instance. E.g.:: my_alias = aliased(MyClass) session.query(MyClass, my_alias).filter(MyClass.id > my_alias.id) The :func:`.aliased` function is used to create an ad-hoc mapping of a mapped class to a new selectable. By default, a selectable is generated from the normally mapped selectable (typically a :class:`_schema.Table` ) using the :meth:`_expression.FromClause.alias` method. However, :func:`.aliased` can also be used to link the class to a new :func:`_expression.select` statement. Also, the :func:`.with_polymorphic` function is a variant of :func:`.aliased` that is intended to specify a so-called "polymorphic selectable", that corresponds to the union of several joined-inheritance subclasses at once. For convenience, the :func:`.aliased` function also accepts plain :class:`_expression.FromClause` constructs, such as a :class:`_schema.Table` or :func:`_expression.select` construct. In those cases, the :meth:`_expression.FromClause.alias` method is called on the object and the new :class:`_expression.Alias` object returned. The returned :class:`_expression.Alias` is not ORM-mapped in this case. .. seealso:: :ref:`tutorial_orm_entity_aliases` - in the :ref:`unified_tutorial` :ref:`orm_queryguide_orm_aliases` - in the :ref:`queryguide_toplevel` :param element: element to be aliased. Is normally a mapped class, but for convenience can also be a :class:`_expression.FromClause` element. :param alias: Optional selectable unit to map the element to. This is usually used to link the object to a subquery, and should be an aliased select construct as one would produce from the :meth:`_query.Query.subquery` method or the :meth:`_expression.Select.subquery` or :meth:`_expression.Select.alias` methods of the :func:`_expression.select` construct. :param name: optional string name to use for the alias, if not specified by the ``alias`` parameter. The name, among other things, forms the attribute name that will be accessible via tuples returned by a :class:`_query.Query` object. Not supported when creating aliases of :class:`_sql.Join` objects. :param flat: Boolean, will be passed through to the :meth:`_expression.FromClause.alias` call so that aliases of :class:`_expression.Join` objects will alias the individual tables inside the join, rather than creating a subquery. This is generally supported by all modern databases with regards to right-nested joins and generally produces more efficient queries. :param adapt_on_names: if True, more liberal "matching" will be used when mapping the mapped columns of the ORM entity to those of the given selectable - a name-based match will be performed if the given selectable doesn't otherwise have a column that corresponds to one on the entity. The use case for this is when associating an entity with some derived selectable such as one that uses aggregate functions:: class UnitPrice(Base): __tablename__ = 'unit_price' ... unit_id = Column(Integer) price = Column(Numeric) aggregated_unit_price = Session.query( func.sum(UnitPrice.price).label('price') ).group_by(UnitPrice.unit_id).subquery() aggregated_unit_price = aliased(UnitPrice, alias=aggregated_unit_price, adapt_on_names=True) Above, functions on ``aggregated_unit_price`` which refer to ``.price`` will return the ``func.sum(UnitPrice.price).label('price')`` column, as it is matched on the name "price". Ordinarily, the "price" function wouldn't have any "column correspondence" to the actual ``UnitPrice.price`` column as it is not a proxy of the original. """ if isinstance(element, expression.FromClause): if adapt_on_names: raise sa_exc.ArgumentError( "adapt_on_names only applies to ORM elements" ) if name: return element.alias(name=name, flat=flat) else: return coercions.expect( roles.AnonymizedFromClauseRole, element, flat=flat ) else: return AliasedClass( element, alias=alias, flat=flat, name=name, adapt_on_names=adapt_on_names, ) def with_polymorphic( base, classes, selectable=False, flat=False, polymorphic_on=None, aliased=False, adapt_on_names=False, innerjoin=False, _use_mapper_path=False, _existing_alias=None, ): """Produce an :class:`.AliasedClass` construct which specifies columns for descendant mappers of the given base. Using this method will ensure that each descendant mapper's tables are included in the FROM clause, and will allow filter() criterion to be used against those tables. The resulting instances will also have those columns already loaded so that no "post fetch" of those columns will be required. .. seealso:: :ref:`with_polymorphic` - full discussion of :func:`_orm.with_polymorphic`. :param base: Base class to be aliased. :param classes: a single class or mapper, or list of class/mappers, which inherit from the base class. Alternatively, it may also be the string ``'*'``, in which case all descending mapped classes will be added to the FROM clause. :param aliased: when True, the selectable will be aliased. For a JOIN, this means the JOIN will be SELECTed from inside of a subquery unless the :paramref:`_orm.with_polymorphic.flat` flag is set to True, which is recommended for simpler use cases. :param flat: Boolean, will be passed through to the :meth:`_expression.FromClause.alias` call so that aliases of :class:`_expression.Join` objects will alias the individual tables inside the join, rather than creating a subquery. This is generally supported by all modern databases with regards to right-nested joins and generally produces more efficient queries. Setting this flag is recommended as long as the resulting SQL is functional. :param selectable: a table or subquery that will be used in place of the generated FROM clause. This argument is required if any of the desired classes use concrete table inheritance, since SQLAlchemy currently cannot generate UNIONs among tables automatically. If used, the ``selectable`` argument must represent the full set of tables and columns mapped by every mapped class. Otherwise, the unaccounted mapped columns will result in their table being appended directly to the FROM clause which will usually lead to incorrect results. When left at its default value of ``False``, the polymorphic selectable assigned to the base mapper is used for selecting rows. However, it may also be passed as ``None``, which will bypass the configured polymorphic selectable and instead construct an ad-hoc selectable for the target classes given; for joined table inheritance this will be a join that includes all target mappers and their subclasses. :param polymorphic_on: a column to be used as the "discriminator" column for the given selectable. If not given, the polymorphic_on attribute of the base classes' mapper will be used, if any. This is useful for mappings that don't have polymorphic loading behavior by default. :param innerjoin: if True, an INNER JOIN will be used. This should only be specified if querying for one specific subtype only :param adapt_on_names: Passes through the :paramref:`_orm.aliased.adapt_on_names` parameter to the aliased object. This may be useful in situations where the given selectable is not directly related to the existing mapped selectable. .. versionadded:: 1.4.33 """ primary_mapper = _class_to_mapper(base) if selectable not in (None, False) and flat: raise sa_exc.ArgumentError( "the 'flat' and 'selectable' arguments cannot be passed " "simultaneously to with_polymorphic()" ) if _existing_alias: assert _existing_alias.mapper is primary_mapper classes = util.to_set(classes) new_classes = set( [mp.class_ for mp in _existing_alias.with_polymorphic_mappers] ) if classes == new_classes: return _existing_alias else: classes = classes.union(new_classes) mappers, selectable = primary_mapper._with_polymorphic_args( classes, selectable, innerjoin=innerjoin ) if aliased or flat: selectable = selectable._anonymous_fromclause(flat=flat) return AliasedClass( base, selectable, adapt_on_names=adapt_on_names, with_polymorphic_mappers=mappers, with_polymorphic_discriminator=polymorphic_on, use_mapper_path=_use_mapper_path, represents_outer_join=not innerjoin, ) @inspection._self_inspects class Bundle( ORMColumnsClauseRole, SupportsCloneAnnotations, sql_base.MemoizedHasCacheKey, InspectionAttr, ): """A grouping of SQL expressions that are returned by a :class:`.Query` under one namespace. The :class:`.Bundle` essentially allows nesting of the tuple-based results returned by a column-oriented :class:`_query.Query` object. It also is extensible via simple subclassing, where the primary capability to override is that of how the set of expressions should be returned, allowing post-processing as well as custom return types, without involving ORM identity-mapped classes. .. versionadded:: 0.9.0 .. seealso:: :ref:`bundles` """ single_entity = False """If True, queries for a single Bundle will be returned as a single entity, rather than an element within a keyed tuple.""" is_clause_element = False is_mapper = False is_aliased_class = False is_bundle = True _propagate_attrs = util.immutabledict() def __init__(self, name, *exprs, **kw): r"""Construct a new :class:`.Bundle`. e.g.:: bn = Bundle("mybundle", MyClass.x, MyClass.y) for row in session.query(bn).filter( bn.c.x == 5).filter(bn.c.y == 4): print(row.mybundle.x, row.mybundle.y) :param name: name of the bundle. :param \*exprs: columns or SQL expressions comprising the bundle. :param single_entity=False: if True, rows for this :class:`.Bundle` can be returned as a "single entity" outside of any enclosing tuple in the same manner as a mapped entity. """ self.name = self._label = name self.exprs = exprs = [ coercions.expect( roles.ColumnsClauseRole, expr, apply_propagate_attrs=self ) for expr in exprs ] self.c = self.columns = ColumnCollection( (getattr(col, "key", col._label), col) for col in [e._annotations.get("bundle", e) for e in exprs] ) self.single_entity = kw.pop("single_entity", self.single_entity) def _gen_cache_key(self, anon_map, bindparams): return (self.__class__, self.name, self.single_entity) + tuple( [expr._gen_cache_key(anon_map, bindparams) for expr in self.exprs] ) @property def mapper(self): return self.exprs[0]._annotations.get("parentmapper", None) @property def entity(self): return self.exprs[0]._annotations.get("parententity", None) @property def entity_namespace(self): return self.c columns = None """A namespace of SQL expressions referred to by this :class:`.Bundle`. e.g.:: bn = Bundle("mybundle", MyClass.x, MyClass.y) q = sess.query(bn).filter(bn.c.x == 5) Nesting of bundles is also supported:: b1 = Bundle("b1", Bundle('b2', MyClass.a, MyClass.b), Bundle('b3', MyClass.x, MyClass.y) ) q = sess.query(b1).filter( b1.c.b2.c.a == 5).filter(b1.c.b3.c.y == 9) .. seealso:: :attr:`.Bundle.c` """ c = None """An alias for :attr:`.Bundle.columns`.""" def _clone(self): cloned = self.__class__.__new__(self.__class__) cloned.__dict__.update(self.__dict__) return cloned def __clause_element__(self): # ensure existing entity_namespace remains annotations = {"bundle": self, "entity_namespace": self} annotations.update(self._annotations) plugin_subject = self.exprs[0]._propagate_attrs.get( "plugin_subject", self.entity ) return ( expression.ClauseList( _literal_as_text_role=roles.ColumnsClauseRole, group=False, *[e._annotations.get("bundle", e) for e in self.exprs] ) ._annotate(annotations) ._set_propagate_attrs( # the Bundle *must* use the orm plugin no matter what. the # subject can be None but it's much better if it's not. { "compile_state_plugin": "orm", "plugin_subject": plugin_subject, } ) ) @property def clauses(self): return self.__clause_element__().clauses def label(self, name): """Provide a copy of this :class:`.Bundle` passing a new label.""" cloned = self._clone() cloned.name = name return cloned def create_row_processor(self, query, procs, labels): """Produce the "row processing" function for this :class:`.Bundle`. May be overridden by subclasses. .. seealso:: :ref:`bundles` - includes an example of subclassing. """ keyed_tuple = result_tuple(labels, [() for l in labels]) def proc(row): return keyed_tuple([proc(row) for proc in procs]) return proc def _orm_annotate(element, exclude=None): """Deep copy the given ClauseElement, annotating each element with the "_orm_adapt" flag. Elements within the exclude collection will be cloned but not annotated. """ return sql_util._deep_annotate(element, {"_orm_adapt": True}, exclude) def _orm_deannotate(element): """Remove annotations that link a column to a particular mapping. Note this doesn't affect "remote" and "foreign" annotations passed by the :func:`_orm.foreign` and :func:`_orm.remote` annotators. """ return sql_util._deep_deannotate( element, values=("_orm_adapt", "parententity") ) def _orm_full_deannotate(element): return sql_util._deep_deannotate(element) class _ORMJoin(expression.Join): """Extend Join to support ORM constructs as input.""" __visit_name__ = expression.Join.__visit_name__ inherit_cache = True def __init__( self, left, right, onclause=None, isouter=False, full=False, _left_memo=None, _right_memo=None, _extra_criteria=(), ): left_info = inspection.inspect(left) right_info = inspection.inspect(right) adapt_to = right_info.selectable # used by joined eager loader self._left_memo = _left_memo self._right_memo = _right_memo # legacy, for string attr name ON clause. if that's removed # then the "_joined_from_info" concept can go left_orm_info = getattr(left, "_joined_from_info", left_info) self._joined_from_info = right_info if isinstance(onclause, util.string_types): onclause = getattr(left_orm_info.entity, onclause) # #### if isinstance(onclause, attributes.QueryableAttribute): on_selectable = onclause.comparator._source_selectable() prop = onclause.property _extra_criteria += onclause._extra_criteria elif isinstance(onclause, MapperProperty): # used internally by joined eager loader...possibly not ideal prop = onclause on_selectable = prop.parent.selectable else: prop = None if prop: left_selectable = left_info.selectable if sql_util.clause_is_present(on_selectable, left_selectable): adapt_from = on_selectable else: adapt_from = left_selectable ( pj, sj, source, dest, secondary, target_adapter, ) = prop._create_joins( source_selectable=adapt_from, dest_selectable=adapt_to, source_polymorphic=True, of_type_entity=right_info, alias_secondary=True, extra_criteria=_extra_criteria, ) if sj is not None: if isouter: # note this is an inner join from secondary->right right = sql.join(secondary, right, sj) onclause = pj else: left = sql.join(left, secondary, pj, isouter) onclause = sj else: onclause = pj self._target_adapter = target_adapter # we don't use the normal coercions logic for _ORMJoin # (probably should), so do some gymnastics to get the entity. # logic here is for #8721, which was a major bug in 1.4 # for almost two years, not reported/fixed until 1.4.43 (!) if left_info.is_selectable: parententity = left_selectable._annotations.get( "parententity", None ) elif left_info.is_mapper or left_info.is_aliased_class: parententity = left_info else: parententity = None if parententity is not None: self._annotations = self._annotations.union( {"parententity": parententity} ) augment_onclause = onclause is None and _extra_criteria expression.Join.__init__(self, left, right, onclause, isouter, full) if augment_onclause: self.onclause &= sql.and_(*_extra_criteria) if ( not prop and getattr(right_info, "mapper", None) and right_info.mapper.single ): # if single inheritance target and we are using a manual # or implicit ON clause, augment it the same way we'd augment the # WHERE. single_crit = right_info.mapper._single_table_criterion if single_crit is not None: if right_info.is_aliased_class: single_crit = right_info._adapter.traverse(single_crit) self.onclause = self.onclause & single_crit def _splice_into_center(self, other): """Splice a join into the center. Given join(a, b) and join(b, c), return join(a, b).join(c) """ leftmost = other while isinstance(leftmost, sql.Join): leftmost = leftmost.left assert self.right is leftmost left = _ORMJoin( self.left, other.left, self.onclause, isouter=self.isouter, _left_memo=self._left_memo, _right_memo=other._left_memo, ) return _ORMJoin( left, other.right, other.onclause, isouter=other.isouter, _right_memo=other._right_memo, ) def join( self, right, onclause=None, isouter=False, full=False, join_to_left=None, ): return _ORMJoin(self, right, onclause, full=full, isouter=isouter) def outerjoin(self, right, onclause=None, full=False, join_to_left=None): return _ORMJoin(self, right, onclause, isouter=True, full=full) def join( left, right, onclause=None, isouter=False, full=False, join_to_left=None ): r"""Produce an inner join between left and right clauses. :func:`_orm.join` is an extension to the core join interface provided by :func:`_expression.join()`, where the left and right selectables may be not only core selectable objects such as :class:`_schema.Table`, but also mapped classes or :class:`.AliasedClass` instances. The "on" clause can be a SQL expression or an ORM mapped attribute referencing a configured :func:`_orm.relationship`. .. deprecated:: 1.4 using a string relationship name for the "onclause" is deprecated and will be removed in 2.0; the onclause may be only an ORM-mapped relationship attribute or a SQL expression construct. :func:`_orm.join` is not commonly needed in modern usage, as its functionality is encapsulated within that of the :meth:`_sql.Select.join` and :meth:`_query.Query.join` methods. which feature a significant amount of automation beyond :func:`_orm.join` by itself. Explicit use of :func:`_orm.join` with ORM-enabled SELECT statements involves use of the :meth:`_sql.Select.select_from` method, as in:: from sqlalchemy.orm import join stmt = select(User).\ select_from(join(User, Address, User.addresses)).\ filter(Address.email_address=='foo@bar.com') In modern SQLAlchemy the above join can be written more succinctly as:: stmt = select(User).\ join(User.addresses).\ filter(Address.email_address=='foo@bar.com') .. warning:: using :func:`_orm.join` directly may not work properly with modern ORM options such as :func:`_orm.with_loader_criteria`. It is strongly recommended to use the idiomatic join patterns provided by methods such as :meth:`.Select.join` and :meth:`.Select.join_from` when creating ORM joins. .. seealso:: :ref:`orm_queryguide_joins` - in the :ref:`queryguide_toplevel` for background on idiomatic ORM join patterns """ return _ORMJoin(left, right, onclause, isouter, full) def outerjoin(left, right, onclause=None, full=False, join_to_left=None): """Produce a left outer join between left and right clauses. This is the "outer join" version of the :func:`_orm.join` function, featuring the same behavior except that an OUTER JOIN is generated. See that function's documentation for other usage details. """ return _ORMJoin(left, right, onclause, True, full) def with_parent(instance, prop, from_entity=None): """Create filtering criterion that relates this query's primary entity to the given related instance, using established :func:`_orm.relationship()` configuration. E.g.:: stmt = select(Address).where(with_parent(some_user, User.addresses)) The SQL rendered is the same as that rendered when a lazy loader would fire off from the given parent on that attribute, meaning that the appropriate state is taken from the parent object in Python without the need to render joins to the parent table in the rendered statement. The given property may also make use of :meth:`_orm.PropComparator.of_type` to indicate the left side of the criteria:: a1 = aliased(Address) a2 = aliased(Address) stmt = select(a1, a2).where( with_parent(u1, User.addresses.of_type(a2)) ) The above use is equivalent to using the :func:`_orm.with_parent.from_entity` argument:: a1 = aliased(Address) a2 = aliased(Address) stmt = select(a1, a2).where( with_parent(u1, User.addresses, from_entity=a2) ) :param instance: An instance which has some :func:`_orm.relationship`. :param property: String property name, or class-bound attribute, which indicates what relationship from the instance should be used to reconcile the parent/child relationship. .. deprecated:: 1.4 Using strings is deprecated and will be removed in SQLAlchemy 2.0. Please use the class-bound attribute directly. :param from_entity: Entity in which to consider as the left side. This defaults to the "zero" entity of the :class:`_query.Query` itself. .. versionadded:: 1.2 """ if isinstance(prop, util.string_types): util.warn_deprecated_20( "Using strings to indicate relationship names in the ORM " "with_parent() function is deprecated and will be removed " "SQLAlchemy 2.0. Please use the class-bound attribute directly." ) mapper = object_mapper(instance) prop = getattr(mapper.class_, prop).property elif isinstance(prop, attributes.QueryableAttribute): if prop._of_type: from_entity = prop._of_type prop = prop.property return prop._with_parent(instance, from_entity=from_entity) def has_identity(object_): """Return True if the given object has a database identity. This typically corresponds to the object being in either the persistent or detached state. .. seealso:: :func:`.was_deleted` """ state = attributes.instance_state(object_) return state.has_identity def was_deleted(object_): """Return True if the given object was deleted within a session flush. This is regardless of whether or not the object is persistent or detached. .. seealso:: :attr:`.InstanceState.was_deleted` """ state = attributes.instance_state(object_) return state.was_deleted def _entity_corresponds_to(given, entity): """determine if 'given' corresponds to 'entity', in terms of an entity passed to Query that would match the same entity being referred to elsewhere in the query. """ if entity.is_aliased_class: if given.is_aliased_class: if entity._base_alias() is given._base_alias(): return True return False elif given.is_aliased_class: if given._use_mapper_path: return entity in given.with_polymorphic_mappers else: return entity is given return entity.common_parent(given) def _entity_corresponds_to_use_path_impl(given, entity): """determine if 'given' corresponds to 'entity', in terms of a path of loader options where a mapped attribute is taken to be a member of a parent entity. e.g.:: someoption(A).someoption(A.b) # -> fn(A, A) -> True someoption(A).someoption(C.d) # -> fn(A, C) -> False a1 = aliased(A) someoption(a1).someoption(A.b) # -> fn(a1, A) -> False someoption(a1).someoption(a1.b) # -> fn(a1, a1) -> True wp = with_polymorphic(A, [A1, A2]) someoption(wp).someoption(A1.foo) # -> fn(wp, A1) -> False someoption(wp).someoption(wp.A1.foo) # -> fn(wp, wp.A1) -> True """ if given.is_aliased_class: return ( entity.is_aliased_class and not entity._use_mapper_path and (given is entity or given in entity._with_polymorphic_entities) ) elif not entity.is_aliased_class: return given.common_parent(entity.mapper) else: return ( entity._use_mapper_path and given in entity.with_polymorphic_mappers ) def _entity_isa(given, mapper): """determine if 'given' "is a" mapper, in terms of the given would load rows of type 'mapper'. """ if given.is_aliased_class: return mapper in given.with_polymorphic_mappers or given.mapper.isa( mapper ) elif given.with_polymorphic_mappers: return mapper in given.with_polymorphic_mappers else: return given.isa(mapper) def randomize_unitofwork(): """Use random-ordering sets within the unit of work in order to detect unit of work sorting issues. This is a utility function that can be used to help reproduce inconsistent unit of work sorting issues. For example, if two kinds of objects A and B are being inserted, and B has a foreign key reference to A - the A must be inserted first. However, if there is no relationship between A and B, the unit of work won't know to perform this sorting, and an operation may or may not fail, depending on how the ordering works out. Since Python sets and dictionaries have non-deterministic ordering, such an issue may occur on some runs and not on others, and in practice it tends to have a great dependence on the state of the interpreter. This leads to so-called "heisenbugs" where changing entirely irrelevant aspects of the test program still cause the failure behavior to change. By calling ``randomize_unitofwork()`` when a script first runs, the ordering of a key series of sets within the unit of work implementation are randomized, so that the script can be minimized down to the fundamental mapping and operation that's failing, while still reproducing the issue on at least some runs. This utility is also available when running the test suite via the ``--reversetop`` flag. """ from sqlalchemy.orm import unitofwork, session, mapper, dependency from sqlalchemy.util import topological from sqlalchemy.testing.util import RandomSet topological.set = ( unitofwork.set ) = session.set = mapper.set = dependency.set = RandomSet def _getitem(iterable_query, item, allow_negative): """calculate __getitem__ in terms of an iterable query object that also has a slice() method. """ def _no_negative_indexes(): if not allow_negative: raise IndexError( "negative indexes are not accepted by SQL " "index / slice operators" ) else: util.warn_deprecated_20( "Support for negative indexes for SQL index / slice operators " "will be " "removed in 2.0; these operators fetch the complete result " "and do not work efficiently." ) if isinstance(item, slice): start, stop, step = util.decode_slice(item) if ( isinstance(stop, int) and isinstance(start, int) and stop - start <= 0 ): return [] elif (isinstance(start, int) and start < 0) or ( isinstance(stop, int) and stop < 0 ): _no_negative_indexes() return list(iterable_query)[item] res = iterable_query.slice(start, stop) if step is not None: return list(res)[None : None : item.step] else: return list(res) else: if item == -1: _no_negative_indexes() return list(iterable_query)[-1] else: return list(iterable_query[item : item + 1])[0]