Merge "Support state expiration for with_expression(); rename deferred_expression"

5 files changed, 27 insertions, 13 deletions

diff --git a/lib/sqlalchemy/orm/__init__.py b/lib/sqlalchemy/orm/__init__.py
index 80c27e392..846d2c2a7 100644
--- a/lib/sqlalchemy/orm/__init__.py
+++ b/lib/sqlalchemy/orm/__init__.py
@@ -178,18 +178,18 @@ def deferred(*columns, **kw):
     return ColumnProperty(deferred=True, *columns, **kw)
 
 
-def deferred_expression():
+def query_expression():
     """Indicate an attribute that populates from a query-time SQL expression.
 
     .. versionadded:: 1.2
 
     .. seealso::
 
-        :ref:`mapper_deferred_expression`
+        :ref:`mapper_query_expression`
 
     """
     prop = ColumnProperty(_sql.null())
-    prop.strategy_key = (("deferred_expression", True),)
+    prop.strategy_key = (("query_expression", True),)
     return prop
 
 mapper = public_factory(Mapper, ".orm.mapper")
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index f3a5c4735..01cb0056e 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -388,7 +388,7 @@ class AttributeImpl(object):
                  callable_, dispatch, trackparent=False, extension=None,
                  compare_function=None, active_history=False,
                  parent_token=None, expire_missing=True,
-                 send_modified_events=True,
+                 send_modified_events=True, accepts_scalar_loader=None,
                  **kwargs):
         r"""Construct an AttributeImpl.
 
@@ -449,6 +449,11 @@ class AttributeImpl(object):
         else:
             self.is_equal = compare_function
 
+        if accepts_scalar_loader is not None:
+            self.accepts_scalar_loader = accepts_scalar_loader
+        else:
+            self.accepts_scalar_loader = self.default_accepts_scalar_loader
+
         # TODO: pass in the manager here
         # instead of doing a lookup
         attr = manager_of_class(class_)[key]
@@ -465,7 +470,7 @@ class AttributeImpl(object):
     __slots__ = (
         'class_', 'key', 'callable_', 'dispatch', 'trackparent',
         'parent_token', 'send_modified_events', 'is_equal', 'expire_missing',
-        '_modified_token'
+        '_modified_token', 'accepts_scalar_loader'
     )
 
     def _init_modified_token(self):
@@ -657,7 +662,7 @@ class AttributeImpl(object):
 class ScalarAttributeImpl(AttributeImpl):
     """represents a scalar value-holding InstrumentedAttribute."""
 
-    accepts_scalar_loader = True
+    default_accepts_scalar_loader = True
     uses_objects = False
     supports_population = True
     collection = False
@@ -743,7 +748,7 @@ class ScalarObjectAttributeImpl(ScalarAttributeImpl):
 
     """
 
-    accepts_scalar_loader = False
+    default_accepts_scalar_loader = False
     uses_objects = True
     supports_population = True
     collection = False
@@ -867,7 +872,7 @@ class CollectionAttributeImpl(AttributeImpl):
     semantics to the orm layer independent of the user data implementation.
 
     """
-    accepts_scalar_loader = False
+    default_accepts_scalar_loader = False
     uses_objects = True
     supports_population = True
     collection = True
diff --git a/lib/sqlalchemy/orm/dynamic.py b/lib/sqlalchemy/orm/dynamic.py
index 9f99740d9..bb63067b0 100644
--- a/lib/sqlalchemy/orm/dynamic.py
+++ b/lib/sqlalchemy/orm/dynamic.py
@@ -44,7 +44,7 @@ class DynaLoader(strategies.AbstractRelationshipLoader):
 
 class DynamicAttributeImpl(attributes.AttributeImpl):
     uses_objects = True
-    accepts_scalar_loader = False
+    default_accepts_scalar_loader = False
     supports_population = False
     collection = False
 
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py
index 4e7636cf8..4b9eb3b0f 100644
--- a/lib/sqlalchemy/orm/strategies.py
+++ b/lib/sqlalchemy/orm/strategies.py
@@ -195,7 +195,7 @@ class ColumnLoader(LoaderStrategy):
 
 
 @log.class_logger
-@properties.ColumnProperty.strategy_for(deferred_expression=True)
+@properties.ColumnProperty.strategy_for(query_expression=True)
 class ExpressionColumnLoader(ColumnLoader):
     def __init__(self, parent, strategy_key):
         super(ExpressionColumnLoader, self).__init__(parent, strategy_key)
@@ -235,6 +235,15 @@ class ExpressionColumnLoader(ColumnLoader):
             else:
                 populators["expire"].append((self.key, True))
 
+    def init_class_attribute(self, mapper):
+        self.is_class_level = True
+
+        _register_attribute(
+            self.parent_property, mapper, useobject=False,
+            compare_function=self.columns[0].type.compare_values,
+            accepts_scalar_loader=False
+        )
+
 
 @log.class_logger
 @properties.ColumnProperty.strategy_for(deferred=True, instrument=True)
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}
     )