diff options
Diffstat (limited to 'lib/sqlalchemy/orm/query.py')
| -rw-r--r-- | lib/sqlalchemy/orm/query.py | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/lib/sqlalchemy/orm/query.py b/lib/sqlalchemy/orm/query.py index 94c6e1776..e53eedda2 100644 --- a/lib/sqlalchemy/orm/query.py +++ b/lib/sqlalchemy/orm/query.py @@ -6,11 +6,11 @@ """The Query class and support. -Defines the :class:`~sqlalchemy.orm.query.Query` class, the central +Defines the :class:`.Query` class, the central construct used by the ORM to construct database queries. -The ``Query`` class should not be confused with the -:class:`~sqlalchemy.sql.expression.Select` class, which defines database +The :class:`.Query` class should not be confused with the +:class:`.Select` class, which defines database SELECT operations at the SQL (non-ORM) level. ``Query`` differs from ``Select`` in that it returns ORM-mapped objects and interacts with an ORM session, whereas the ``Select`` construct interacts directly with the @@ -596,6 +596,25 @@ class Query(object): @_generative() def correlate(self, *args): + """Return a :class:`.Query` construct which will correlate the given + FROM clauses to that of an enclosing :class:`.Query` or + :func:`~.expression.select`. + + The method here accepts mapped classes, :func:`.aliased` constructs, + and :func:`.mapper` constructs as arguments, which are resolved into + expression constructs, in addition to appropriate expression + constructs. + + The correlation arguments are ultimately passed to + :meth:`.Select.correlate` after coercion to expression constructs. + + The correlation arguments take effect in such cases + as when :meth:`.Query.from_self` is used, or when + a subquery as returned by :meth:`.Query.subquery` is + embedded in another :func:`~.expression.select` construct. + + """ + self._correlate = self._correlate.union( _orm_selectable(s) for s in args) @@ -2547,8 +2566,12 @@ class _MapperEntity(_QueryEntity): ) ) - for value in self.mapper._iterate_polymorphic_properties( - self._with_polymorphic): + if self._with_polymorphic: + poly_properties = self.mapper._iterate_polymorphic_properties( + self._with_polymorphic) + else: + poly_properties = self.mapper._polymorphic_properties + for value in poly_properties: if query._only_load_props and \ value.key not in query._only_load_props: continue |