- [bug] Fixed event registration bug

which would primarily show up as
events not being registered with
sessionmaker() instances created
after the event was associated
with the Session class.  [ticket:2424]

1 files changed, 26 insertions, 9 deletions

diff --git a/lib/sqlalchemy/event.py b/lib/sqlalchemy/event.py
index 9cc3139af..cd70b3a7c 100644
--- a/lib/sqlalchemy/event.py
+++ b/lib/sqlalchemy/event.py
@@ -13,12 +13,12 @@ NO_RETVAL = util.symbol('NO_RETVAL')
 
 def listen(target, identifier, fn, *args, **kw):
     """Register a listener function for the given target.
-    
+
     e.g.::
-    
+
         from sqlalchemy import event
         from sqlalchemy.schema import UniqueConstraint
-        
+
         def unique_constraint_name(const, table):
             const.name = "uq_%s_%s" % (
                 table.name,
@@ -41,12 +41,12 @@ def listen(target, identifier, fn, *args, **kw):
 
 def listens_for(target, identifier, *args, **kw):
     """Decorate a function as a listener for the given target + identifier.
-    
+
     e.g.::
-    
+
         from sqlalchemy import event
         from sqlalchemy.schema import UniqueConstraint
-        
+
         @event.listens_for(UniqueConstraint, "after_parent_attach")
         def unique_constraint_name(const, table):
             const.name = "uq_%s_%s" % (
@@ -205,12 +205,14 @@ class _DispatchDescriptor(object):
     def insert(self, obj, target, propagate):
         assert isinstance(target, type), \
                 "Class-level Event targets must be classes."
-
         stack = [target]
         while stack:
             cls = stack.pop(0)
             stack.extend(cls.__subclasses__())
-            self._clslevel[cls].insert(0, obj)
+            if cls is not target and cls not in self._clslevel:
+                self.update_subclass(cls)
+            else:
+                self._clslevel[cls].insert(0, obj)
 
     def append(self, obj, target, propagate):
         assert isinstance(target, type), \
@@ -220,7 +222,20 @@ class _DispatchDescriptor(object):
         while stack:
             cls = stack.pop(0)
             stack.extend(cls.__subclasses__())
-            self._clslevel[cls].append(obj)
+            if cls is not target and cls not in self._clslevel:
+                self.update_subclass(cls)
+            else:
+                self._clslevel[cls].append(obj)
+
+    def update_subclass(self, target):
+        clslevel = self._clslevel[target]
+        for cls in target.__mro__[1:]:
+            if cls in self._clslevel:
+                clslevel.extend([
+                    fn for fn 
+                    in self._clslevel[cls] 
+                    if fn not in clslevel
+                ])
 
     def remove(self, obj, target):
         stack = [target]
@@ -252,6 +267,8 @@ class _ListenerCollection(object):
     _exec_once = False
 
     def __init__(self, parent, target_cls):
+        if target_cls not in parent._clslevel:
+            parent.update_subclass(target_cls)
         self.parent_listeners = parent._clslevel[target_cls]
         self.name = parent.__name__
         self.listeners = []