- Fixed bug that affected generally the same classes of event

as that of :ticket:`3199`, when the ``named=True`` parameter
would be used.  Some events would fail to register, and others
would not invoke the event arguments correctly, generally in the
case of when an event was "wrapped" for adaption in some other way.
The "named" mechanics have been rearranged to not interfere with
the argument signature expected by internal wrapper functions.
fixes #3197

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/sqlalchemy/event/registry.py b/lib/sqlalchemy/event/registry.py
index 217cf7d44..5b422c401 100644
--- a/lib/sqlalchemy/event/registry.py
+++ b/lib/sqlalchemy/event/registry.py
@@ -182,6 +182,17 @@ class _EventKey(object):
 
     def listen(self, *args, **kw):
         once = kw.pop("once", False)
+        named = kw.pop("named", False)
+
+        target, identifier, fn = \
+            self.dispatch_target, self.identifier, self._listen_fn
+
+        dispatch_descriptor = getattr(target.dispatch, identifier)
+
+        adjusted_fn = dispatch_descriptor._adjust_fn_spec(fn, named)
+
+        self = self.with_wrapper(adjusted_fn)
+
         if once:
             self.with_wrapper(
                 util.only_once(self._listen_fn)).listen(*args, **kw)
@@ -217,9 +228,6 @@ class _EventKey(object):
 
         dispatch_descriptor = getattr(target.dispatch, identifier)
 
-        fn = dispatch_descriptor._adjust_fn_spec(fn, named)
-        self = self.with_wrapper(fn)
-
         if insert:
             dispatch_descriptor.\
                 for_modify(target.dispatch).insert(self, propagate)