- Fixed bug whereby changing a primary key attribute on an

entity where the attribute's previous value had been expired
would produce an error upon flush(). [ticket:1151]

2 files changed, 12 insertions, 7 deletions

diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 6fd134242..88e124e4b 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -217,12 +217,17 @@ class AttributeImpl(object):
           to it via this attribute.
 
         extension
-          an AttributeExtension object which will receive
-          set/delete/append/remove/etc. events.
+          a single or list of AttributeExtension object(s) which will 
+          receive set/delete/append/remove/etc. events.
 
         compare_function
           a function that compares two values which are normally
           assignable to this attribute.
+        
+        active_history
+          indicates that get_history() should always return the "old" value,
+          even if it means executing a lazy callable upon attribute change.
+          This flag is set to True if any extensions are present.
 
         """
 
@@ -231,12 +236,12 @@ class AttributeImpl(object):
         self.callable_ = callable_
         self.class_manager = class_manager
         self.trackparent = trackparent
-        self.active_history = active_history
         if compare_function is None:
             self.is_equal = operator.eq
         else:
             self.is_equal = compare_function
         self.extensions = util.to_list(extension or [])
+        self.active_history = active_history or bool(self.extensions)
 
     def hasparent(self, state, optimistic=False):
         """Return the boolean value of a `hasparent` flag attached to the given item.
@@ -367,7 +372,7 @@ class ScalarAttributeImpl(AttributeImpl):
     def delete(self, state):
 
         # TODO: catch key errors, convert to attributeerror?
-        if self.active_history or self.extensions:
+        if self.active_history:
             old = self.get(state)
         else:
             old = state.dict.get(self.key, NO_VALUE)
@@ -388,7 +393,7 @@ class ScalarAttributeImpl(AttributeImpl):
         if initiator is self:
             return
 
-        if self.active_history or self.extensions:
+        if self.active_history:
             old = self.get(state)
         else:
             old = state.dict.get(self.key, NO_VALUE)
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 20bb85e80..b46ae16d3 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1220,15 +1220,15 @@ class Session(object):
             merged_state._run_on_load(merged)
         return merged
 
+    @classmethod
     def identity_key(cls, *args, **kwargs):
         return mapperutil.identity_key(*args, **kwargs)
-    identity_key = classmethod(identity_key)
 
+    @classmethod
     def object_session(cls, instance):
         """Return the ``Session`` to which an object belongs."""
 
         return object_session(instance)
-    object_session = classmethod(object_session)
 
     def _validate_persistent(self, state):
         if not self.identity_map.contains_state(state):