Merge "Fixes for uselist=True with m2o relationships"

3 files changed, 23 insertions, 3 deletions

diff --git a/lib/sqlalchemy/orm/dependency.py b/lib/sqlalchemy/orm/dependency.py
index f0ba6051d..e93ad9eb7 100644
--- a/lib/sqlalchemy/orm/dependency.py
+++ b/lib/sqlalchemy/orm/dependency.py
@@ -938,7 +938,13 @@ class DetectKeySwitch(DependencyProcessor):
                     related is not attributes.PASSIVE_NO_RESULT
                     and related is not None
                 ):
-                    related_state = attributes.instance_state(dict_[self.key])
+                    if self.prop.uselist:
+                        if not related:
+                            continue
+                        related_obj = related[0]
+                    else:
+                        related_obj = related
+                    related_state = attributes.instance_state(related_obj)
                     if related_state in switchers:
                         uowcommit.register_object(
                             state, False, self.passive_updates
diff --git a/lib/sqlalchemy/orm/dynamic.py b/lib/sqlalchemy/orm/dynamic.py
index 20544dbbe..3218b9fa3 100644
--- a/lib/sqlalchemy/orm/dynamic.py
+++ b/lib/sqlalchemy/orm/dynamic.py
@@ -14,6 +14,7 @@ basic add/delete mutation.
 
 from . import attributes
 from . import exc as orm_exc
+from . import interfaces
 from . import object_mapper
 from . import object_session
 from . import properties
@@ -36,6 +37,17 @@ class DynaLoader(strategies.AbstractRelationshipLoader):
                 "many-to-one/one-to-one relationships and/or "
                 "uselist=False." % self.parent_property
             )
+        elif self.parent_property.direction not in (
+            interfaces.ONETOMANY,
+            interfaces.MANYTOMANY,
+        ):
+            util.warn(
+                "On relationship %s, 'dynamic' loaders cannot be used with "
+                "many-to-one/one-to-one relationships and/or "
+                "uselist=False.  This warning will be an exception in a "
+                "future release." % self.parent_property
+            )
+
         strategies._register_attribute(
             self.parent_property,
             mapper,
diff --git a/lib/sqlalchemy/testing/entities.py b/lib/sqlalchemy/testing/entities.py
index b894979d0..cbc7a2fd5 100644
--- a/lib/sqlalchemy/testing/entities.py
+++ b/lib/sqlalchemy/testing/entities.py
@@ -7,7 +7,7 @@
 
 import sqlalchemy as sa
 from .. import exc as sa_exc
-
+from ..util import compat
 
 _repr_stack = set()
 
@@ -90,7 +90,9 @@ class ComparableEntity(BasicEntity):
                 except (AttributeError, sa_exc.UnboundExecutionError):
                     return False
 
-                if hasattr(value, "__iter__"):
+                if hasattr(value, "__iter__") and not isinstance(
+                    value, compat.string_types
+                ):
                     if hasattr(value, "__getitem__") and not hasattr(
                         value, "keys"
                     ):