From efdd638cd253f656cb1d6d47e961040c0ca0b855 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 28 Nov 2007 22:03:14 +0000
Subject: [PATCH] - fixed bug which could arise when using
 session.begin_nested() in conjunction with more than one level deep of
 enclosing session.begin() statements

---
 CHANGES                       |  3 +++
 lib/sqlalchemy/orm/session.py |  5 +++--
 test/orm/session.py           | 23 +++++++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/CHANGES b/CHANGES
index 936204e381..d6607e935d 100644
--- a/CHANGES
+++ b/CHANGES
@@ -48,6 +48,9 @@ CHANGES
      We also copy the instances over without using any events now, so that
      the 'dirty' list on the new session remains unaffected.
 
+   - fixed bug which could arise when using session.begin_nested() in conjunction
+     with more than one level deep of enclosing session.begin() statements
+     
 - dialects
 
    - MSSQL/PyODBC no longer has a global "set nocount on".
diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index b8995140e9..6b6d678359 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -175,8 +175,9 @@ class SessionTransaction(object):
             if bind in self.__connections:
                 return self.__connections[bind][0]
 
-            if bind in self.__parent._connection_dict():
-                (conn, trans, autoclose) = self.__parent.__connections[bind]
+            conn_dict = self.__parent._connection_dict()
+            if bind in conn_dict:
+                (conn, trans, autoclose) = conn_dict[bind]
                 self.__connections[conn] = self.__connections[bind.engine] = (conn, conn.begin_nested(), autoclose)
                 return conn
         elif bind in self.__connections:
diff --git a/test/orm/session.py b/test/orm/session.py
index 0639a7d950..a662371480 100644
--- a/test/orm/session.py
+++ b/test/orm/session.py
@@ -241,6 +241,29 @@ class SessionTest(AssertMixin):
             conn.close()
             raise
     
+    @testing.supported('postgres', 'mysql')
+    @engines.close_open_connections
+    def test_heavy_nesting(self):
+        session = create_session(bind=testbase.db)
+
+        session.begin()
+        session.connection().execute("insert into users (user_name) values ('user1')")
+
+        session.begin()
+        
+        session.begin_nested()
+
+        session.connection().execute("insert into users (user_name) values ('user2')")
+        assert session.connection().execute("select count(1) from users").scalar() == 2
+
+        session.rollback()
+        assert session.connection().execute("select count(1) from users").scalar() == 1
+        session.connection().execute("insert into users (user_name) values ('user3')")
+
+        session.commit()
+        assert session.connection().execute("select count(1) from users").scalar() == 2
+        
+    
     @testing.supported('postgres', 'mysql')
     @testing.exclude('mysql', '<', (5, 0, 3))
     def test_twophase(self):
-- 
2.47.3