Support state expiration for with_expression(); rename deferred_expression

The attributeimpl for a deferred_expression does not
support a scalar loader, add new configurability so that
the impl can have this flag turned off.   Document
that the with_expression() system currently does not
offer any deferred loading.

To eliminate confusion over "deferred", which refers to
lazy loading of column attributes, and "with_expression",
which refers to an attribute that is explicitly at
query time only, rename deferred_expression to query_expression.

Change-Id: I07c4a050ed68c79ccbde9492e9de1630b7470d74

1 files changed, 3 insertions, 3 deletions

diff --git a/lib/sqlalchemy/orm/strategy_options.py b/lib/sqlalchemy/orm/strategy_options.py
index 2cdf6ba95..796f859f8 100644
--- a/lib/sqlalchemy/orm/strategy_options.py
+++ b/lib/sqlalchemy/orm/strategy_options.py
@@ -1356,7 +1356,7 @@ from .util import _orm_full_deannotate
 def with_expression(loadopt, key, expression):
     r"""Apply an ad-hoc SQL expression to a "deferred expression" attribute.
 
-    This option is used in conjunction with the :func:`.orm.deferred_expression`
+    This option is used in conjunction with the :func:`.orm.query_expression`
     mapper-level construct that indicates an attribute which should be the
     target of an ad-hoc SQL expression.
 
@@ -1375,7 +1375,7 @@ def with_expression(loadopt, key, expression):
 
     .. seealso::
 
-        :ref:`mapper_deferred_expression`
+        :ref:`mapper_query_expression`
 
     """
 
@@ -1384,7 +1384,7 @@ def with_expression(loadopt, key, expression):
 
     return loadopt.set_column_strategy(
         (key, ),
-        {"deferred_expression": True},
+        {"query_expression": True},
         opts={"expression": expression}
     )