Implemented changes made in r14320 in the Oracle backend. Thanks Russell for reviewing the proposed fix.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14510 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/oracle/base.py

@@ -399,6 +399,28 @@ class DatabaseWrapper(BaseDatabaseWrapper):
     def _savepoint_commit(self, sid):
         pass
 
+    def _commit(self):
+        if self.connection is not None:
+            try:
+                return self.connection.commit()
+            except Database.IntegrityError, e:
+                # In case cx_Oracle implements (now or in a future version)
+                # raising this specific exception
+                raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
+            except Database.DatabaseError, e:
+                # cx_Oracle 5.0.4 raises a cx_Oracle.DatabaseError exception
+                # with the following attributes and values:
+                #  code = 2091
+                #  message = 'ORA-02091: transaction rolled back
+                #            'ORA-02291: integrity constraint (TEST_DJANGOTEST.SYS
+                #               _C00102056) violated - parent key not found'
+                # We convert that particular case to our IntegrityError exception
+                x = e.args[0]
+                if hasattr(x, 'code') and hasattr(x, 'message') \
+                   and x.code == 2091 and 'ORA-02291' in x.message:
+                    raise utils.IntegrityError, utils.IntegrityError(*tuple(e)), sys.exc_info()[2]
+                raise utils.DatabaseError, utils.DatabaseError(*tuple(e)), sys.exc_info()[2]
+
 
 class OracleParam(object):
     """