diff options
Diffstat (limited to 'lib/sqlalchemy/orm/mapper.py')
| -rw-r--r-- | lib/sqlalchemy/orm/mapper.py | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py index 88dadcc22..53afdcb28 100644 --- a/lib/sqlalchemy/orm/mapper.py +++ b/lib/sqlalchemy/orm/mapper.py @@ -112,6 +112,7 @@ class Mapper(InspectionAttr): include_properties=None, exclude_properties=None, passive_updates=True, + passive_deletes=False, confirm_deleted_rows=True, eager_defaults=False, legacy_is_orphan=False, @@ -319,6 +320,40 @@ class Mapper(InspectionAttr): ordering for entities. By default mappers have no pre-defined ordering. + :param passive_deletes: Indicates DELETE behavior of foreign key + columns when a joined-table inheritance entity is being deleted. + Defaults to ``False`` for a base mapper; for an inheriting mapper, + defaults to ``False`` unless the value is set to ``True`` + on the superclass mapper. + + When ``True``, it is assumed that ON DELETE CASCADE is configured + on the foreign key relationships that link this mapper's table + to its superclass table, so that when the unit of work attempts + to delete the entity, it need only emit a DELETE statement for the + superclass table, and not this table. + + When ``False``, a DELETE statement is emitted for this mapper's + table individually. If the primary key attributes local to this + table are unloaded, then a SELECT must be emitted in order to + validate these attributes; note that the primary key columns + of a joined-table subclass are not part of the "primary key" of + the object as a whole. + + Note that a value of ``True`` is **always** forced onto the + subclass mappers; that is, it's not possible for a superclass + to specify passive_deletes without this taking effect for + all subclass mappers. + + .. versionadded:: 1.1 + + .. seealso:: + + :ref:`passive_deletes` - description of similar feature as + used with :func:`.relationship` + + :paramref:`.mapper.passive_updates` - supporting ON UPDATE + CASCADE for joined-table inheritance mappers + :param passive_updates: Indicates UPDATE behavior of foreign key columns when a primary key column changes on a joined-table inheritance mapping. Defaults to ``True``. @@ -339,6 +374,9 @@ class Mapper(InspectionAttr): :ref:`passive_updates` - description of a similar feature as used with :func:`.relationship` + :paramref:`.mapper.passive_deletes` - supporting ON DELETE + CASCADE for joined-table inheritance mappers + :param polymorphic_on: Specifies the column, attribute, or SQL expression used to determine the target class for an incoming row, when inheriting classes are present. @@ -559,6 +597,7 @@ class Mapper(InspectionAttr): self._dependency_processors = [] self.validators = util.immutabledict() self.passive_updates = passive_updates + self.passive_deletes = passive_deletes self.legacy_is_orphan = legacy_is_orphan self._clause_adapter = None self._requires_row_aliasing = False @@ -971,6 +1010,8 @@ class Mapper(InspectionAttr): self.inherits._inheriting_mappers.append(self) self.base_mapper = self.inherits.base_mapper self.passive_updates = self.inherits.passive_updates + self.passive_deletes = self.inherits.passive_deletes or \ + self.passive_deletes self._all_tables = self.inherits._all_tables if self.polymorphic_identity is not None: @@ -982,7 +1023,7 @@ class Mapper(InspectionAttr): (self.polymorphic_identity, self.polymorphic_map[self.polymorphic_identity], self, self.polymorphic_identity) - ) + ) self.polymorphic_map[self.polymorphic_identity] = self else: |