- Fixed a regression from 0.7 where the contextmanager feature

of :meth:`.Session.begin_nested` would fail to correctly
roll back the transaction when a flush error occurred, instead
raising its own exception while leaving the session still
pending a rollback.  [ticket:2718]

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index f7a5558f1..ffb8a4e03 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -169,6 +169,7 @@ class SessionTransaction(object):
 
     def _assert_active(self, prepared_ok=False,
                         rollback_ok=False,
+                        deactive_ok=False,
                         closed_msg="This transaction is closed"):
         if self._state is COMMITTED:
             raise sa_exc.InvalidRequestError(
@@ -182,7 +183,7 @@ class SessionTransaction(object):
                         "SQL can be emitted within this transaction."
                     )
         elif self._state is DEACTIVE:
-            if not rollback_ok:
+            if not deactive_ok and not rollback_ok:
                 if self._rollback_exception:
                     raise sa_exc.InvalidRequestError(
                         "This Session's transaction has been rolled back "
@@ -192,7 +193,7 @@ class SessionTransaction(object):
                         " Original exception was: %s"
                         % self._rollback_exception
                     )
-                else:
+                elif not deactive_ok:
                     raise sa_exc.InvalidRequestError(
                         "This Session's transaction has been rolled back "
                         "by a nested rollback() call.  To begin a new "
@@ -435,7 +436,7 @@ class SessionTransaction(object):
         return self
 
     def __exit__(self, type, value, traceback):
-        self._assert_active(prepared_ok=True)
+        self._assert_active(deactive_ok=True, prepared_ok=True)
         if self.session.transaction is None:
             return
         if type is None: