- A rare case which occurs when a :meth:`.Session.rollback` fails in the

scope of a :meth:`.Session.flush` operation that's raising an
exception, as has been observed in some MySQL SAVEPOINT cases, prevents
the original  database exception from being observed when it was
emitted during  flush, but only on Py2K because Py2K does not support
exception  chaining; on Py3K the originating exception is chained.  As
a workaround, a warning is emitted in this specific case showing at
least the string message of the original database error before we
proceed to raise  the rollback-originating exception.
fixes #2696

(cherry picked from commit a6fe4dc0c8ebc346a90dd849a86dac9345d74515)

diff --git a/doc/build/changelog/changelog_10.rst b/doc/build/changelog/changelog_10.rst
index c800647a6972a6bb8a3492911f62598819d8b631..40a251a222cc77d1c439486a1e4cec605833b200 100644 (file)
--- a/doc/build/changelog/changelog_10.rst
+++ b/doc/build/changelog/changelog_10.rst
@@ -18,6 +18,21 @@
 .. changelog::
     :version: 1.0.10
 
+    .. change::
+        :tags: bug, orm
+        :versions: 1.1.0b1
+        :tickets: 2696
+
+        A rare case which occurs when a :meth:`.Session.rollback` fails in the
+        scope of a :meth:`.Session.flush` operation that's raising an
+        exception, as has been observed in some MySQL SAVEPOINT cases, prevents
+        the original  database exception from being observed when it was
+        emitted during  flush, but only on Py2K because Py2K does not support
+        exception  chaining; on Py3K the originating exception is chained.  As
+        a workaround, a warning is emitted in this specific case showing at
+        least the string message of the original database error before we
+        proceed to raise  the rollback-originating exception.
+
     .. change::
         :tags: bug, postgresql
         :versions: 1.1.0b1

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 6c3f392bac15b4884d233e8ddfe3d7e749e91b52..17808e66bacec79ca3d3434a17df9c30211fedd2 100644 (file)
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -412,11 +412,23 @@ class SessionTransaction(object):
             for subtransaction in stx._iterate_parents(upto=self):
                 subtransaction.close()
 
+        if _capture_exception:
+            captured_exception = sys.exc_info()[1]
+
         boundary = self
         if self._state in (ACTIVE, PREPARED):
             for transaction in self._iterate_parents():
                 if transaction._parent is None or transaction.nested:
-                    transaction._rollback_impl()
+                    try:
+                        transaction._rollback_impl()
+                    except Exception:
+                        if _capture_exception:
+                            util.warn(
+                                "An exception raised during a Session "
+                                "persistence operation cannot be raised "
+                                "due to an additional ROLLBACK exception; "
+                                "the exception is: %s" % captured_exception)
+                        raise
                     transaction._state = DEACTIVE
                     boundary = transaction
                     break
@@ -438,7 +450,7 @@ class SessionTransaction(object):
 
         self.close()
         if self._parent and _capture_exception:
-            self._parent._rollback_exception = sys.exc_info()[1]
+            self._parent._rollback_exception = captured_exception
 
         sess.dispatch.after_soft_rollback(sess, self)
 

diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index 21dc3e71aca609c383f1d84448e9be5f51c49acd..63667654d44f020bac610ea0426b8c9e4adc8abf 100644 (file)
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -121,7 +121,7 @@ def uses_deprecated(*messages):
 def _expect_warnings(exc_cls, messages, regex=True, assert_=True):
 
     if regex:
-        filters = [re.compile(msg, re.I) for msg in messages]
+        filters = [re.compile(msg, re.I | re.S) for msg in messages]
     else:
         filters = messages
 

diff --git a/test/orm/test_transaction.py b/test/orm/test_transaction.py
index 91846a67e6102347d512e7be66702c05746215d9..6918996a027b02b586a7ba9ca7e7ca3a832cf7ca 100644 (file)
--- a/test/orm/test_transaction.py
+++ b/test/orm/test_transaction.py
@@ -657,6 +657,31 @@ class SessionTransactionTest(FixtureTest):
         assert session.transaction is not None, \
             'autocommit=False should start a new transaction'
 
+    @testing.requires.savepoints
+    def test_report_primary_error_when_rollback_fails(self):
+        User, users = self.classes.User, self.tables.users
+
+        mapper(User, users)
+
+        session = Session(testing.db)
+
+        with expect_warnings(".*due to an additional ROLLBACK.*INSERT INTO"):
+            session.begin_nested()
+            savepoint = session.\
+                connection()._Connection__transaction._savepoint
+
+            # force the savepoint to disappear
+            session.execute("RELEASE SAVEPOINT %s" % savepoint)
+
+            # now do a broken flush
+            session.add_all([User(id=1), User(id=1)])
+
+            assert_raises_message(
+                sa_exc.DBAPIError,
+                "ROLLBACK TO SAVEPOINT ",
+                session.flush
+            )
+
 
 class _LocalFixture(FixtureTest):
     run_setup_mappers = 'once'