- Fixed bug in mutable extension as well as

:func:`.attributes.flag_modified` where the change event would not be
propagated if the attribute had been reassigned to itself.
fixes #2997

3 files changed, 6 insertions, 3 deletions

diff --git a/lib/sqlalchemy/ext/mutable.py b/lib/sqlalchemy/ext/mutable.py
index 4e574935d..7869e888c 100644
--- a/lib/sqlalchemy/ext/mutable.py
+++ b/lib/sqlalchemy/ext/mutable.py
@@ -437,6 +437,9 @@ class MutableBase(object):
             outgoing.
 
             """
+            if value is oldvalue:
+                return value
+
             if not isinstance(value, cls):
                 value = cls.coerce(key, value)
             if value is not None:
diff --git a/lib/sqlalchemy/orm/attributes.py b/lib/sqlalchemy/orm/attributes.py
index 7647bf9d0..3a786c73d 100644
--- a/lib/sqlalchemy/orm/attributes.py
+++ b/lib/sqlalchemy/orm/attributes.py
@@ -1538,4 +1538,4 @@ def flag_modified(instance, key):
     """
     state, dict_ = instance_state(instance), instance_dict(instance)
     impl = state.manager[key].impl
-    state._modified_event(dict_, impl, NO_VALUE)
+    state._modified_event(dict_, impl, NO_VALUE, force=True)
diff --git a/lib/sqlalchemy/orm/state.py b/lib/sqlalchemy/orm/state.py
index 9712dd055..fb5db1fc9 100644
--- a/lib/sqlalchemy/orm/state.py
+++ b/lib/sqlalchemy/orm/state.py
@@ -414,10 +414,10 @@ class InstanceState(interfaces._InspectionAttr):
     def _instance_dict(self):
         return None
 
-    def _modified_event(self, dict_, attr, previous, collection=False):
+    def _modified_event(self, dict_, attr, previous, collection=False, force=False):
         if not attr.send_modified_events:
             return
-        if attr.key not in self.committed_state:
+        if attr.key not in self.committed_state or force:
             if collection:
                 if previous is NEVER_SET:
                     if attr.key in dict_: