diff options
Diffstat (limited to 'lib/sqlalchemy/ext/declarative/extensions.py')
| -rw-r--r-- | lib/sqlalchemy/ext/declarative/extensions.py | 45 |
1 files changed, 23 insertions, 22 deletions
diff --git a/lib/sqlalchemy/ext/declarative/extensions.py b/lib/sqlalchemy/ext/declarative/extensions.py index 87fc702cf..29eb76e82 100644 --- a/lib/sqlalchemy/ext/declarative/extensions.py +++ b/lib/sqlalchemy/ext/declarative/extensions.py @@ -134,8 +134,8 @@ class AbstractConcreteBase(ConcreteBase): .. note:: - The :class:`.AbstractConcreteBase` class does not intend to set up the - mapping for the base class until all the subclasses have been defined, + The :class:`.AbstractConcreteBase` delays the mapper creation of the + base class until all the subclasses have been defined, as it needs to create a mapping against a selectable that will include all subclass tables. In order to achieve this, it waits for the **mapper configuration event** to occur, at which point it scans @@ -145,23 +145,22 @@ class AbstractConcreteBase(ConcreteBase): While this event is normally invoked automatically, in the case of :class:`.AbstractConcreteBase`, it may be necessary to invoke it explicitly after **all** subclass mappings are defined, if the first - operation is to be a query against this base class. To do so, invoke - :func:`.configure_mappers` once all the desired classes have been - configured:: - - from sqlalchemy.orm import configure_mappers - - configure_mappers() - - .. seealso:: - - :func:`_orm.configure_mappers` + operation is to be a query against this base class. To do so, once all + the desired classes have been configured, the + :meth:`_orm.registry.configure` method on the :class:`_orm.registry` + in use can be invoked, which is available in relation to a particular + declarative base class:: + Base.registry.configure() Example:: + from sqlalchemy.orm import DeclarativeBase from sqlalchemy.ext.declarative import AbstractConcreteBase + class Base(DeclarativeBase): + pass + class Employee(AbstractConcreteBase, Base): pass @@ -173,9 +172,10 @@ class AbstractConcreteBase(ConcreteBase): __mapper_args__ = { 'polymorphic_identity':'manager', - 'concrete':True} + 'concrete':True + } - configure_mappers() + Base.registry.configure() The abstract base class is handled by declarative in a special way; at class configuration time, it behaves like a declarative mixin @@ -211,18 +211,17 @@ class AbstractConcreteBase(ConcreteBase): __mapper_args__ = { 'polymorphic_identity':'manager', - 'concrete':True} + 'concrete':True + } - configure_mappers() + Base.registry.configure() When we make use of our mappings however, both ``Manager`` and ``Employee`` will have an independently usable ``.company`` attribute:: - session.query(Employee).filter(Employee.company.has(id=5)) - - .. versionchanged:: 1.0.0 - The mechanics of :class:`.AbstractConcreteBase` - have been reworked to support relationships established directly - on the abstract base, without any special configurational steps. + session.execute( + select(Employee).filter(Employee.company.has(id=5)) + ) .. seealso:: @@ -230,6 +229,8 @@ class AbstractConcreteBase(ConcreteBase): :ref:`concrete_inheritance` + :ref:`abstract_concrete_base` + """ __no_table__ = True |