# orm/properties.py # Copyright (C) 2005-2014 the SQLAlchemy authors and contributors # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php """MapperProperty implementations. This is a private module which defines the behavior of invidual ORM- mapped attributes. """ from .. import sql, util, log, exc as sa_exc, inspect from ..sql import operators, expression from . import ( attributes, mapper, strategies, configure_mappers, relationships, dependency ) from .util import CascadeOptions, \ _orm_annotate, _orm_deannotate, _orm_full_deannotate from .interfaces import MANYTOMANY, MANYTOONE, ONETOMANY,\ PropComparator, StrategizedProperty mapperlib = util.importlater("sqlalchemy.orm", "mapperlib") NoneType = type(None) from descriptor_props import CompositeProperty, SynonymProperty, \ ComparableProperty, ConcreteInheritedProperty __all__ = ['ColumnProperty', 'CompositeProperty', 'SynonymProperty', 'ComparableProperty', 'RelationshipProperty', 'RelationProperty'] class ColumnProperty(StrategizedProperty): """Describes an object attribute that corresponds to a table column. Public constructor is the :func:`.orm.column_property` function. """ def __init__(self, *columns, **kwargs): """Construct a ColumnProperty. Note the public constructor is the :func:`.orm.column_property` function. :param \*columns: The list of `columns` describes a single object property. If there are multiple tables joined together for the mapper, this list represents the equivalent column as it appears across each table. :param group: :param deferred: :param comparator_factory: :param descriptor: :param expire_on_flush: :param extension: :param info: Optional data dictionary which will be populated into the :attr:`.info` attribute of this object. """ self._orig_columns = [expression._labeled(c) for c in columns] self.columns = [expression._labeled(_orm_full_deannotate(c)) for c in columns] self.group = kwargs.pop('group', None) self.deferred = kwargs.pop('deferred', False) self.instrument = kwargs.pop('_instrument', True) self.comparator_factory = kwargs.pop('comparator_factory', self.__class__.Comparator) self.descriptor = kwargs.pop('descriptor', None) self.extension = kwargs.pop('extension', None) self.active_history = kwargs.pop('active_history', False) self.expire_on_flush = kwargs.pop('expire_on_flush', True) if 'info' in kwargs: self.info = kwargs.pop('info') if 'doc' in kwargs: self.doc = kwargs.pop('doc') else: for col in reversed(self.columns): doc = getattr(col, 'doc', None) if doc is not None: self.doc = doc break else: self.doc = None if kwargs: raise TypeError( "%s received unexpected keyword argument(s): %s" % ( self.__class__.__name__, ', '.join(sorted(kwargs.keys())))) util.set_creation_order(self) if not self.instrument: self.strategy_class = strategies.UninstrumentedColumnLoader elif self.deferred: self.strategy_class = strategies.DeferredColumnLoader else: self.strategy_class = strategies.ColumnLoader @property def expression(self): """Return the primary column or expression for this ColumnProperty. """ return self.columns[0] def instrument_class(self, mapper): if not self.instrument: return attributes.register_descriptor( mapper.class_, self.key, comparator=self.comparator_factory(self, mapper), parententity=mapper, doc=self.doc ) def do_init(self): super(ColumnProperty, self).do_init() if len(self.columns) > 1 and \ set(self.parent.primary_key).issuperset(self.columns): util.warn( ("On mapper %s, primary key column '%s' is being combined " "with distinct primary key column '%s' in attribute '%s'. " "Use explicit properties to give each column its own mapped " "attribute name.") % (self.parent, self.columns[1], self.columns[0], self.key)) def copy(self): return ColumnProperty( deferred=self.deferred, group=self.group, active_history=self.active_history, *self.columns) def _getcommitted(self, state, dict_, column, passive=attributes.PASSIVE_OFF): return state.get_impl(self.key).\ get_committed_value(state, dict_, passive=passive) def merge(self, session, source_state, source_dict, dest_state, dest_dict, load, _recursive): if not self.instrument: return elif self.key in source_dict: value = source_dict[self.key] if not load: dest_dict[self.key] = value else: impl = dest_state.get_impl(self.key) impl.set(dest_state, dest_dict, value, None) elif dest_state.has_identity and self.key not in dest_dict: dest_state._expire_attributes(dest_dict, [self.key]) class Comparator(PropComparator): """Produce boolean, comparison, and other operators for :class:`.ColumnProperty` attributes. See the documentation for :class:`.PropComparator` for a brief overview. See also: :class:`.PropComparator` :class:`.ColumnOperators` :ref:`types_operators` :attr:`.TypeEngine.comparator_factory` """ @util.memoized_instancemethod def __clause_element__(self): if self.adapter: return self.adapter(self.prop.columns[0]) else: return self.prop.columns[0]._annotate({ "parententity": self._parentmapper, "parentmapper": self._parentmapper}) @util.memoized_property def info(self): ce = self.__clause_element__() try: return ce.info except AttributeError: return self.prop.info def __getattr__(self, key): """proxy attribute access down to the mapped column. this allows user-defined comparison methods to be accessed. """ return getattr(self.__clause_element__(), key) def operate(self, op, *other, **kwargs): return op(self.__clause_element__(), *other, **kwargs) def reverse_operate(self, op, other, **kwargs): col = self.__clause_element__() return op(col._bind_param(op, other), col, **kwargs) # TODO: legacy..do we need this ? (0.5) ColumnComparator = Comparator def __str__(self): return str(self.parent.class_.__name__) + "." + self.key log.class_logger(ColumnProperty) class RelationshipProperty(StrategizedProperty): """Describes an object property that holds a single item or list of items that correspond to a related database table. Public constructor is the :func:`.orm.relationship` function. See also: :ref:`relationship_config_toplevel` """ strategy_wildcard_key = 'relationship:*' _dependency_processor = None def __init__(self, argument, secondary=None, primaryjoin=None, secondaryjoin=None, foreign_keys=None, uselist=None, order_by=False, backref=None, back_populates=None, post_update=False, cascade=False, extension=None, viewonly=False, lazy=True, collection_class=None, passive_deletes=False, passive_updates=True, remote_side=None, enable_typechecks=True, join_depth=None, comparator_factory=None, single_parent=False, innerjoin=False, distinct_target_key=False, doc=None, active_history=False, cascade_backrefs=True, load_on_pending=False, strategy_class=None, _local_remote_pairs=None, query_class=None, info=None): self.uselist = uselist self.argument = argument self.secondary = secondary self.primaryjoin = primaryjoin self.secondaryjoin = secondaryjoin self.post_update = post_update self.direction = None self.viewonly = viewonly self.lazy = lazy self.single_parent = single_parent self._user_defined_foreign_keys = foreign_keys self.collection_class = collection_class self.passive_deletes = passive_deletes self.cascade_backrefs = cascade_backrefs self.passive_updates = passive_updates self.remote_side = remote_side self.enable_typechecks = enable_typechecks self.query_class = query_class self.innerjoin = innerjoin self.distinct_target_key = distinct_target_key self.doc = doc self.active_history = active_history self.join_depth = join_depth self.local_remote_pairs = _local_remote_pairs self.extension = extension self.load_on_pending = load_on_pending self.comparator_factory = comparator_factory or \ RelationshipProperty.Comparator self.comparator = self.comparator_factory(self, None) util.set_creation_order(self) if info is not None: self.info = info if strategy_class: self.strategy_class = strategy_class elif self.lazy == 'dynamic': from sqlalchemy.orm import dynamic self.strategy_class = dynamic.DynaLoader else: self.strategy_class = strategies.factory(self.lazy) self._reverse_property = set() self.cascade = cascade if cascade is not False \ else "save-update, merge" self.order_by = order_by self.back_populates = back_populates if self.back_populates: if backref: raise sa_exc.ArgumentError( "backref and back_populates keyword arguments " "are mutually exclusive") self.backref = None else: self.backref = backref def instrument_class(self, mapper): attributes.register_descriptor( mapper.class_, self.key, comparator=self.comparator_factory(self, mapper), parententity=mapper, doc=self.doc, ) class Comparator(PropComparator): """Produce boolean, comparison, and other operators for :class:`.RelationshipProperty` attributes. See the documentation for :class:`.PropComparator` for a brief overview of ORM level operator definition. See also: :class:`.PropComparator` :class:`.ColumnProperty.Comparator` :class:`.ColumnOperators` :ref:`types_operators` :attr:`.TypeEngine.comparator_factory` """ _of_type = None def __init__(self, prop, parentmapper, of_type=None, adapter=None): """Construction of :class:`.RelationshipProperty.Comparator` is internal to the ORM's attribute mechanics. """ self.prop = prop self._parentmapper = parentmapper self.adapter = adapter if of_type: self._of_type = of_type def adapted(self, adapter): """Return a copy of this PropComparator which will use the given adaption function on the local side of generated expressions. """ return self.__class__(self.property, self._parentmapper, getattr(self, '_of_type', None), adapter) @util.memoized_property def mapper(self): """The target :class:`.Mapper` referred to by this :class:`.RelationshipProperty.Comparator. This is the "target" or "remote" side of the :func:`.relationship`. """ return self.property.mapper @util.memoized_property def _parententity(self): return self.property.parent def _source_selectable(self): elem = self.property.parent._with_polymorphic_selectable if self.adapter: return self.adapter(elem) else: return elem def __clause_element__(self): adapt_from = self._source_selectable() if self._of_type: of_type = inspect(self._of_type).mapper else: of_type = None pj, sj, source, dest, \ secondary, target_adapter = self.property._create_joins( source_selectable=adapt_from, source_polymorphic=True, of_type=of_type) if sj is not None: return pj & sj else: return pj def of_type(self, cls): """Produce a construct that represents a particular 'subtype' of attribute for the parent class. Currently this is usable in conjunction with :meth:`.Query.join` and :meth:`.Query.outerjoin`. """ return RelationshipProperty.Comparator( self.property, self._parentmapper, cls, adapter=self.adapter) def in_(self, other): """Produce an IN clause - this is not implemented for :func:`~.orm.relationship`-based attributes at this time. """ raise NotImplementedError('in_() not yet supported for ' 'relationships. For a simple many-to-one, use ' 'in_() against the set of foreign key values.') __hash__ = None def __eq__(self, other): """Implement the ``==`` operator. In a many-to-one context, such as:: MyClass.some_prop == this will typically produce a clause such as:: mytable.related_id == Where ```` is the primary key of the given object. The ``==`` operator provides partial functionality for non- many-to-one comparisons: * Comparisons against collections are not supported. Use :meth:`~.RelationshipProperty.Comparator.contains`. * Compared to a scalar one-to-many, will produce a clause that compares the target columns in the parent to the given target. * Compared to a scalar many-to-many, an alias of the association table will be rendered as well, forming a natural join that is part of the main body of the query. This will not work for queries that go beyond simple AND conjunctions of comparisons, such as those which use OR. Use explicit joins, outerjoins, or :meth:`~.RelationshipProperty.Comparator.has` for more comprehensive non-many-to-one scalar membership tests. * Comparisons against ``None`` given in a one-to-many or many-to-many context produce a NOT EXISTS clause. """ if isinstance(other, (NoneType, expression.Null)): if self.property.direction in [ONETOMANY, MANYTOMANY]: return ~self._criterion_exists() else: return _orm_annotate(self.property._optimized_compare( None, adapt_source=self.adapter)) elif self.property.uselist: raise sa_exc.InvalidRequestError("Can't compare a colle" "ction to an object or collection; use " "contains() to test for membership.") else: return _orm_annotate(self.property._optimized_compare(other, adapt_source=self.adapter)) def _criterion_exists(self, criterion=None, **kwargs): if getattr(self, '_of_type', None): info = inspect(self._of_type) target_mapper, to_selectable, is_aliased_class = \ info.mapper, info.selectable, info.is_aliased_class if self.property._is_self_referential and not is_aliased_class: to_selectable = to_selectable.alias() single_crit = target_mapper._single_table_criterion if single_crit is not None: if criterion is not None: criterion = single_crit & criterion else: criterion = single_crit else: is_aliased_class = False to_selectable = None if self.adapter: source_selectable = self._source_selectable() else: source_selectable = None pj, sj, source, dest, secondary, target_adapter = \ self.property._create_joins(dest_polymorphic=True, dest_selectable=to_selectable, source_selectable=source_selectable) for k in kwargs: crit = getattr(self.property.mapper.class_, k) == kwargs[k] if criterion is None: criterion = crit else: criterion = criterion & crit # annotate the *local* side of the join condition, in the case # of pj + sj this is the full primaryjoin, in the case of just # pj its the local side of the primaryjoin. if sj is not None: j = _orm_annotate(pj) & sj else: j = _orm_annotate(pj, exclude=self.property.remote_side) if criterion is not None and target_adapter and not is_aliased_class: # limit this adapter to annotated only? criterion = target_adapter.traverse(criterion) # only have the "joined left side" of what we # return be subject to Query adaption. The right # side of it is used for an exists() subquery and # should not correlate or otherwise reach out # to anything in the enclosing query. if criterion is not None: criterion = criterion._annotate( {'no_replacement_traverse': True}) crit = j & criterion ex = sql.exists([1], crit, from_obj=dest).correlate_except(dest) if secondary is not None: ex = ex.correlate_except(secondary) return ex def any(self, criterion=None, **kwargs): """Produce an expression that tests a collection against particular criterion, using EXISTS. An expression like:: session.query(MyClass).filter( MyClass.somereference.any(SomeRelated.x==2) ) Will produce a query like:: SELECT * FROM my_table WHERE EXISTS (SELECT 1 FROM related WHERE related.my_id=my_table.id AND related.x=2) Because :meth:`~.RelationshipProperty.Comparator.any` uses a correlated subquery, its performance is not nearly as good when compared against large target tables as that of using a join. :meth:`~.RelationshipProperty.Comparator.any` is particularly useful for testing for empty collections:: session.query(MyClass).filter( ~MyClass.somereference.any() ) will produce:: SELECT * FROM my_table WHERE NOT EXISTS (SELECT 1 FROM related WHERE related.my_id=my_table.id) :meth:`~.RelationshipProperty.Comparator.any` is only valid for collections, i.e. a :func:`.relationship` that has ``uselist=True``. For scalar references, use :meth:`~.RelationshipProperty.Comparator.has`. """ if not self.property.uselist: raise sa_exc.InvalidRequestError( "'any()' not implemented for scalar " "attributes. Use has()." ) return self._criterion_exists(criterion, **kwargs) def has(self, criterion=None, **kwargs): """Produce an expression that tests a scalar reference against particular criterion, using EXISTS. An expression like:: session.query(MyClass).filter( MyClass.somereference.has(SomeRelated.x==2) ) Will produce a query like:: SELECT * FROM my_table WHERE EXISTS (SELECT 1 FROM related WHERE related.id==my_table.related_id AND related.x=2) Because :meth:`~.RelationshipProperty.Comparator.has` uses a correlated subquery, its performance is not nearly as good when compared against large target tables as that of using a join. :meth:`~.RelationshipProperty.Comparator.has` is only valid for scalar references, i.e. a :func:`.relationship` that has ``uselist=False``. For collection references, use :meth:`~.RelationshipProperty.Comparator.any`. """ if self.property.uselist: raise sa_exc.InvalidRequestError( "'has()' not implemented for collections. " "Use any().") return self._criterion_exists(criterion, **kwargs) def contains(self, other, **kwargs): """Return a simple expression that tests a collection for containment of a particular item. :meth:`~.RelationshipProperty.Comparator.contains` is only valid for a collection, i.e. a :func:`~.orm.relationship` that implements one-to-many or many-to-many with ``uselist=True``. When used in a simple one-to-many context, an expression like:: MyClass.contains(other) Produces a clause like:: mytable.id == Where ```` is the value of the foreign key attribute on ``other`` which refers to the primary key of its parent object. From this it follows that :meth:`~.RelationshipProperty.Comparator.contains` is very useful when used with simple one-to-many operations. For many-to-many operations, the behavior of :meth:`~.RelationshipProperty.Comparator.contains` has more caveats. The association table will be rendered in the statement, producing an "implicit" join, that is, includes multiple tables in the FROM clause which are equated in the WHERE clause:: query(MyClass).filter(MyClass.contains(other)) Produces a query like:: SELECT * FROM my_table, my_association_table AS my_association_table_1 WHERE my_table.id = my_association_table_1.parent_id AND my_association_table_1.child_id = Where ```` would be the primary key of ``other``. From the above, it is clear that :meth:`~.RelationshipProperty.Comparator.contains` will **not** work with many-to-many collections when used in queries that move beyond simple AND conjunctions, such as multiple :meth:`~.RelationshipProperty.Comparator.contains` expressions joined by OR. In such cases subqueries or explicit "outer joins" will need to be used instead. See :meth:`~.RelationshipProperty.Comparator.any` for a less-performant alternative using EXISTS, or refer to :meth:`.Query.outerjoin` as well as :ref:`ormtutorial_joins` for more details on constructing outer joins. """ if not self.property.uselist: raise sa_exc.InvalidRequestError( "'contains' not implemented for scalar " "attributes. Use ==") clause = self.property._optimized_compare(other, adapt_source=self.adapter) if self.property.secondaryjoin is not None: clause.negation_clause = \ self.__negated_contains_or_equals(other) return clause def __negated_contains_or_equals(self, other): if self.property.direction == MANYTOONE: state = attributes.instance_state(other) def state_bindparam(x, state, col): o = state.obj() # strong ref return sql.bindparam(x, unique=True, callable_=lambda: \ self.property.mapper._get_committed_attr_by_column(o, col)) def adapt(col): if self.adapter: return self.adapter(col) else: return col if self.property._use_get: return sql.and_(*[ sql.or_( adapt(x) != state_bindparam(adapt(x), state, y), adapt(x) == None) for (x, y) in self.property.local_remote_pairs]) criterion = sql.and_(*[x == y for (x, y) in zip( self.property.mapper.primary_key, self.property.\ mapper.\ primary_key_from_instance(other)) ]) return ~self._criterion_exists(criterion) def __ne__(self, other): """Implement the ``!=`` operator. In a many-to-one context, such as:: MyClass.some_prop != This will typically produce a clause such as:: mytable.related_id != Where ```` is the primary key of the given object. The ``!=`` operator provides partial functionality for non- many-to-one comparisons: * Comparisons against collections are not supported. Use :meth:`~.RelationshipProperty.Comparator.contains` in conjunction with :func:`~.expression.not_`. * Compared to a scalar one-to-many, will produce a clause that compares the target columns in the parent to the given target. * Compared to a scalar many-to-many, an alias of the association table will be rendered as well, forming a natural join that is part of the main body of the query. This will not work for queries that go beyond simple AND conjunctions of comparisons, such as those which use OR. Use explicit joins, outerjoins, or :meth:`~.RelationshipProperty.Comparator.has` in conjunction with :func:`~.expression.not_` for more comprehensive non-many-to-one scalar membership tests. * Comparisons against ``None`` given in a one-to-many or many-to-many context produce an EXISTS clause. """ if isinstance(other, (NoneType, expression.Null)): if self.property.direction == MANYTOONE: return sql.or_(*[x != None for x in self.property._calculated_foreign_keys]) else: return self._criterion_exists() elif self.property.uselist: raise sa_exc.InvalidRequestError("Can't compare a collection" " to an object or collection; use " "contains() to test for membership.") else: return self.__negated_contains_or_equals(other) @util.memoized_property def property(self): if mapperlib.module._new_mappers: configure_mappers() return self.prop def compare(self, op, value, value_is_parent=False, alias_secondary=True): if op == operators.eq: if value is None: if self.uselist: return ~sql.exists([1], self.primaryjoin) else: return self._optimized_compare(None, value_is_parent=value_is_parent, alias_secondary=alias_secondary) else: return self._optimized_compare(value, value_is_parent=value_is_parent, alias_secondary=alias_secondary) else: return op(self.comparator, value) def _optimized_compare(self, value, value_is_parent=False, adapt_source=None, alias_secondary=True): if value is not None: value = attributes.instance_state(value) return self._get_strategy(strategies.LazyLoader).lazy_clause(value, reverse_direction=not value_is_parent, alias_secondary=alias_secondary, adapt_source=adapt_source) def __str__(self): return str(self.parent.class_.__name__) + "." + self.key def merge(self, session, source_state, source_dict, dest_state, dest_dict, load, _recursive): if load: for r in self._reverse_property: if (source_state, r) in _recursive: return if not "merge" in self._cascade: return if self.key not in source_dict: return if self.uselist: instances = source_state.get_impl(self.key).\ get(source_state, source_dict) if hasattr(instances, '_sa_adapter'): # convert collections to adapters to get a true iterator instances = instances._sa_adapter if load: # for a full merge, pre-load the destination collection, # so that individual _merge of each item pulls from identity # map for those already present. # also assumes CollectionAttrbiuteImpl behavior of loading # "old" list in any case dest_state.get_impl(self.key).get(dest_state, dest_dict) dest_list = [] for current in instances: current_state = attributes.instance_state(current) current_dict = attributes.instance_dict(current) _recursive[(current_state, self)] = True obj = session._merge(current_state, current_dict, load=load, _recursive=_recursive) if obj is not None: dest_list.append(obj) if not load: coll = attributes.init_state_collection(dest_state, dest_dict, self.key) for c in dest_list: coll.append_without_event(c) else: dest_state.get_impl(self.key)._set_iterable(dest_state, dest_dict, dest_list) else: current = source_dict[self.key] if current is not None: current_state = attributes.instance_state(current) current_dict = attributes.instance_dict(current) _recursive[(current_state, self)] = True obj = session._merge(current_state, current_dict, load=load, _recursive=_recursive) else: obj = None if not load: dest_dict[self.key] = obj else: dest_state.get_impl(self.key).set(dest_state, dest_dict, obj, None) def _value_as_iterable(self, state, dict_, key, passive=attributes.PASSIVE_OFF): """Return a list of tuples (state, obj) for the given key. returns an empty list if the value is None/empty/PASSIVE_NO_RESULT """ impl = state.manager[key].impl x = impl.get(state, dict_, passive=passive) if x is attributes.PASSIVE_NO_RESULT or x is None: return [] elif hasattr(impl, 'get_collection'): return [ (attributes.instance_state(o), o) for o in impl.get_collection(state, dict_, x, passive=passive) ] else: return [(attributes.instance_state(x), x)] def cascade_iterator(self, type_, state, dict_, visited_states, halt_on=None): #assert type_ in self._cascade # only actively lazy load on the 'delete' cascade if type_ != 'delete' or self.passive_deletes: passive = attributes.PASSIVE_NO_INITIALIZE else: passive = attributes.PASSIVE_OFF if type_ == 'save-update': tuples = state.manager[self.key].impl.\ get_all_pending(state, dict_) else: tuples = self._value_as_iterable(state, dict_, self.key, passive=passive) skip_pending = type_ == 'refresh-expire' and 'delete-orphan' \ not in self._cascade for instance_state, c in tuples: if instance_state in visited_states: continue if c is None: # would like to emit a warning here, but # would not be consistent with collection.append(None) # current behavior of silently skipping. # see [ticket:2229] continue instance_dict = attributes.instance_dict(c) if halt_on and halt_on(instance_state): continue if skip_pending and not instance_state.key: continue instance_mapper = instance_state.manager.mapper if not instance_mapper.isa(self.mapper.class_manager.mapper): raise AssertionError("Attribute '%s' on class '%s' " "doesn't handle objects " "of type '%s'" % ( self.key, self.parent.class_, c.__class__ )) visited_states.add(instance_state) yield c, instance_mapper, instance_state, instance_dict def _add_reverse_property(self, key): other = self.mapper.get_property(key, _configure_mappers=False) self._reverse_property.add(other) other._reverse_property.add(self) if not other.mapper.common_parent(self.parent): raise sa_exc.ArgumentError('reverse_property %r on ' 'relationship %s references relationship %s, which ' 'does not reference mapper %s' % (key, self, other, self.parent)) if self.direction in (ONETOMANY, MANYTOONE) and self.direction \ == other.direction: raise sa_exc.ArgumentError('%s and back-reference %s are ' 'both of the same direction %r. Did you mean to ' 'set remote_side on the many-to-one side ?' % (other, self, self.direction)) @util.memoized_property def mapper(self): """Return the targeted :class:`.Mapper` for this :class:`.RelationshipProperty`. This is a lazy-initializing static attribute. """ if util.callable(self.argument) and \ not isinstance(self.argument, (type, mapperlib.Mapper)): argument = self.argument() else: argument = self.argument if isinstance(argument, type): mapper_ = mapperlib.class_mapper(argument, configure=False) elif isinstance(self.argument, mapperlib.Mapper): mapper_ = argument else: raise sa_exc.ArgumentError("relationship '%s' expects " "a class or a mapper argument (received: %s)" % (self.key, type(argument))) return mapper_ @util.memoized_property @util.deprecated("0.7", "Use .target") def table(self): """Return the selectable linked to this :class:`.RelationshipProperty` object's target :class:`.Mapper`.""" return self.target def do_init(self): self._check_conflicts() self._process_dependent_arguments() self._setup_join_conditions() self._check_cascade_settings(self._cascade) self._post_init() self._generate_backref() super(RelationshipProperty, self).do_init() def _process_dependent_arguments(self): """Convert incoming configuration arguments to their proper form. Callables are resolved, ORM annotations removed. """ # accept callables for other attributes which may require # deferred initialization. This technique is used # by declarative "string configs" and some recipes. for attr in ( 'order_by', 'primaryjoin', 'secondaryjoin', 'secondary', '_user_defined_foreign_keys', 'remote_side', ): attr_value = getattr(self, attr) if util.callable(attr_value): setattr(self, attr, attr_value()) # remove "annotations" which are present if mapped class # descriptors are used to create the join expression. for attr in 'primaryjoin', 'secondaryjoin': val = getattr(self, attr) if val is not None: setattr(self, attr, _orm_deannotate( expression._only_column_elements(val, attr)) ) # ensure expressions in self.order_by, foreign_keys, # remote_side are all columns, not strings. if self.order_by is not False and self.order_by is not None: self.order_by = [ expression._only_column_elements(x, "order_by") for x in util.to_list(self.order_by)] self._user_defined_foreign_keys = \ util.column_set( expression._only_column_elements(x, "foreign_keys") for x in util.to_column_set( self._user_defined_foreign_keys )) self.remote_side = \ util.column_set( expression._only_column_elements(x, "remote_side") for x in util.to_column_set(self.remote_side)) self.target = self.mapper.mapped_table def _setup_join_conditions(self): self._join_condition = jc = relationships.JoinCondition( parent_selectable=self.parent.mapped_table, child_selectable=self.mapper.mapped_table, parent_local_selectable=self.parent.local_table, child_local_selectable=self.mapper.local_table, primaryjoin=self.primaryjoin, secondary=self.secondary, secondaryjoin=self.secondaryjoin, parent_equivalents=self.parent._equivalent_columns, child_equivalents=self.mapper._equivalent_columns, consider_as_foreign_keys=self._user_defined_foreign_keys, local_remote_pairs=self.local_remote_pairs, remote_side=self.remote_side, self_referential=self._is_self_referential, prop=self, support_sync=not self.viewonly, can_be_synced_fn=self._columns_are_mapped ) self.primaryjoin = jc.deannotated_primaryjoin self.secondaryjoin = jc.deannotated_secondaryjoin self.direction = jc.direction self.local_remote_pairs = jc.local_remote_pairs self.remote_side = jc.remote_columns self.local_columns = jc.local_columns self.synchronize_pairs = jc.synchronize_pairs self._calculated_foreign_keys = jc.foreign_key_columns self.secondary_synchronize_pairs = jc.secondary_synchronize_pairs def _check_conflicts(self): """Test that this relationship is legal, warn about inheritance conflicts.""" if not self.is_primary() \ and not mapper.class_mapper( self.parent.class_, configure=False).has_property(self.key): raise sa_exc.ArgumentError("Attempting to assign a new " "relationship '%s' to a non-primary mapper on " "class '%s'. New relationships can only be added " "to the primary mapper, i.e. the very first mapper " "created for class '%s' " % (self.key, self.parent.class_.__name__, self.parent.class_.__name__)) # check for conflicting relationship() on superclass if not self.parent.concrete: for inheriting in self.parent.iterate_to_root(): if inheriting is not self.parent \ and inheriting.has_property(self.key): util.warn("Warning: relationship '%s' on mapper " "'%s' supersedes the same relationship " "on inherited mapper '%s'; this can " "cause dependency issues during flush" % (self.key, self.parent, inheriting)) def _get_cascade(self): """Return the current cascade setting for this :class:`.RelationshipProperty`. """ return self._cascade def _set_cascade(self, cascade): cascade = CascadeOptions(cascade) if 'mapper' in self.__dict__: self._check_cascade_settings(cascade) self._cascade = cascade if self._dependency_processor: self._dependency_processor.cascade = cascade cascade = property(_get_cascade, _set_cascade) def _check_cascade_settings(self, cascade): if cascade.delete_orphan and not self.single_parent \ and (self.direction is MANYTOMANY or self.direction is MANYTOONE): raise sa_exc.ArgumentError( 'On %s, delete-orphan cascade is not supported ' 'on a many-to-many or many-to-one relationship ' 'when single_parent is not set. Set ' 'single_parent=True on the relationship().' % self) if self.direction is MANYTOONE and self.passive_deletes: util.warn("On %s, 'passive_deletes' is normally configured " "on one-to-many, one-to-one, many-to-many " "relationships only." % self) if self.passive_deletes == 'all' and \ ("delete" in cascade or "delete-orphan" in cascade): raise sa_exc.ArgumentError( "On %s, can't set passive_deletes='all' in conjunction " "with 'delete' or 'delete-orphan' cascade" % self) if cascade.delete_orphan: self.mapper.primary_mapper()._delete_orphans.append( (self.key, self.parent.class_) ) def _columns_are_mapped(self, *cols): """Return True if all columns in the given collection are mapped by the tables referenced by this :class:`.Relationship`. """ for c in cols: if self.secondary is not None \ and self.secondary.c.contains_column(c): continue if not self.parent.mapped_table.c.contains_column(c) and \ not self.target.c.contains_column(c): return False return True def _generate_backref(self): """Interpret the 'backref' instruction to create a :func:`.relationship` complementary to this one.""" if not self.is_primary(): return if self.backref is not None and not self.back_populates: if isinstance(self.backref, basestring): backref_key, kwargs = self.backref, {} else: backref_key, kwargs = self.backref mapper = self.mapper.primary_mapper() check = set(mapper.iterate_to_root()).\ union(mapper.self_and_descendants) for m in check: if m.has_property(backref_key): raise sa_exc.ArgumentError("Error creating backref " "'%s' on relationship '%s': property of that " "name exists on mapper '%s'" % (backref_key, self, m)) # determine primaryjoin/secondaryjoin for the # backref. Use the one we had, so that # a custom join doesn't have to be specified in # both directions. if self.secondary is not None: # for many to many, just switch primaryjoin/ # secondaryjoin. use the annotated # pj/sj on the _join_condition. pj = kwargs.pop('primaryjoin', self._join_condition.secondaryjoin_minus_local) sj = kwargs.pop('secondaryjoin', self._join_condition.primaryjoin_minus_local) else: pj = kwargs.pop('primaryjoin', self._join_condition.primaryjoin_reverse_remote) sj = kwargs.pop('secondaryjoin', None) if sj: raise sa_exc.InvalidRequestError( "Can't assign 'secondaryjoin' on a backref " "against a non-secondary relationship." ) foreign_keys = kwargs.pop('foreign_keys', self._user_defined_foreign_keys) parent = self.parent.primary_mapper() kwargs.setdefault('viewonly', self.viewonly) kwargs.setdefault('post_update', self.post_update) kwargs.setdefault('passive_updates', self.passive_updates) self.back_populates = backref_key relationship = RelationshipProperty( parent, self.secondary, pj, sj, foreign_keys=foreign_keys, back_populates=self.key, **kwargs) mapper._configure_property(backref_key, relationship) if self.back_populates: self._add_reverse_property(self.back_populates) def _post_init(self): if self.uselist is None: self.uselist = self.direction is not MANYTOONE if not self.viewonly: self._dependency_processor = \ dependency.DependencyProcessor.from_relationship(self) @util.memoized_property def _use_get(self): """memoize the 'use_get' attribute of this RelationshipLoader's lazyloader.""" strategy = self._get_strategy(strategies.LazyLoader) return strategy.use_get @util.memoized_property def _is_self_referential(self): return self.mapper.common_parent(self.parent) def _create_joins(self, source_polymorphic=False, source_selectable=None, dest_polymorphic=False, dest_selectable=None, of_type=None): if source_selectable is None: if source_polymorphic and self.parent.with_polymorphic: source_selectable = self.parent._with_polymorphic_selectable aliased = False if dest_selectable is None: if dest_polymorphic and self.mapper.with_polymorphic: dest_selectable = self.mapper._with_polymorphic_selectable aliased = True else: dest_selectable = self.mapper.mapped_table if self._is_self_referential and source_selectable is None: dest_selectable = dest_selectable.alias() aliased = True else: aliased = True dest_mapper = of_type or self.mapper single_crit = dest_mapper._single_table_criterion aliased = aliased or (source_selectable is not None) primaryjoin, secondaryjoin, secondary, target_adapter, dest_selectable = \ self._join_condition.join_targets( source_selectable, dest_selectable, aliased, single_crit ) if source_selectable is None: source_selectable = self.parent.local_table if dest_selectable is None: dest_selectable = self.mapper.local_table return (primaryjoin, secondaryjoin, source_selectable, dest_selectable, secondary, target_adapter) PropertyLoader = RelationProperty = RelationshipProperty log.class_logger(RelationshipProperty)