- don't load deferred columns on unexpire for merge with load=False,pr/256

fixes #3488

Co-Authored-By: Mike Bayer <mike_mp@zzzcomputing.com>

3 files changed, 20 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/properties.py b/lib/sqlalchemy/orm/properties.py
index 8197e041f..f3dce7541 100644
--- a/lib/sqlalchemy/orm/properties.py
+++ b/lib/sqlalchemy/orm/properties.py
@@ -218,7 +218,8 @@ class ColumnProperty(StrategizedProperty):
                 impl = dest_state.get_impl(self.key)
                 impl.set(dest_state, dest_dict, value, None)
         elif dest_state.has_identity and self.key not in dest_dict:
-            dest_state._expire_attributes(dest_dict, [self.key])
+            dest_state._expire_attributes(
+                dest_dict, [self.key], no_loader=True)
 
     class Comparator(util.MemoizedSlots, PropComparator):
         """Produce boolean, comparison, and other operators for
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index dc5de7ac6..1cf1bdb24 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1842,6 +1842,13 @@ class Session(_SessionClassMethods):
             merged_state.load_path = state.load_path
             merged_state.load_options = state.load_options
 
+            # since we are copying load_options, we need to copy
+            # the callables_ that would have been generated by those
+            # load_options.
+            # assumes that the callables we put in state.callables_
+            # are not instance-specific (which they should not be)
+            merged_state._copy_callables(state)
+
             for prop in mapper.iterate_properties:
                 prop.merge(self, state, state_dict,
                            merged_state, merged_dict,
diff --git a/lib/sqlalchemy/orm/state.py b/lib/sqlalchemy/orm/state.py
index 1ad09ee83..2704367f9 100644
--- a/lib/sqlalchemy/orm/state.py
+++ b/lib/sqlalchemy/orm/state.py
@@ -485,6 +485,10 @@ class InstanceState(interfaces.InspectionAttr):
         if self.callables:
             self.callables.pop(key, None)
 
+    def _copy_callables(self, from_):
+        if 'callables' in from_.__dict__:
+            self.callables = dict(from_.callables)
+
     @classmethod
     def _instance_level_callable_processor(cls, manager, fn, key):
         impl = manager[key].impl
@@ -537,7 +541,7 @@ class InstanceState(interfaces.InspectionAttr):
 
         self.manager.dispatch.expire(self, None)
 
-    def _expire_attributes(self, dict_, attribute_names):
+    def _expire_attributes(self, dict_, attribute_names, no_loader=False):
         pending = self.__dict__.get('_pending_mutations', None)
 
         callables = self.callables
@@ -545,6 +549,12 @@ class InstanceState(interfaces.InspectionAttr):
         for key in attribute_names:
             impl = self.manager[key].impl
             if impl.accepts_scalar_loader:
+                if no_loader and (
+                    impl.callable_ or
+                    key in callables
+                ):
+                    continue
+
                 self.expired_attributes.add(key)
                 if callables and key in callables:
                     del callables[key]