- [feature] Added new connection event

dbapi_error(). Is called for all DBAPI-level
errors passing the original DBAPI exception
before SQLAlchemy modifies the state
of the cursor.

2 files changed, 39 insertions, 0 deletions

diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index 1f28501f7..110ac4e8a 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -1806,10 +1806,19 @@ class Connection(Connectable):
                 (statement is not None and context is None)
 
             if should_wrap and context:
+                if self._has_events:
+                    self.engine.dispatch.dbapi_error(self, 
+                                                    cursor, 
+                                                    statement, 
+                                                    parameters, 
+                                                    context, 
+                                                    e)
                 context.handle_dbapi_exception(e)
 
             is_disconnect = isinstance(e, self.dialect.dbapi.Error) and \
                                 self.dialect.is_disconnect(e, self.__connection, cursor)
+
+
             if is_disconnect:
                 self.invalidate(e)
                 self.engine.dispose()
diff --git a/lib/sqlalchemy/events.py b/lib/sqlalchemy/events.py
index 504dfe150..18888be03 100644
--- a/lib/sqlalchemy/events.py
+++ b/lib/sqlalchemy/events.py
@@ -401,6 +401,36 @@ class ConnectionEvents(event.Events):
                         parameters, context, executemany):
         """Intercept low-level cursor execute() events."""
 
+    def dbapi_error(self, conn, cursor, statement, parameters, 
+                        context, exception):
+        """Intercept a raw DBAPI error.
+        
+        This event is called with the DBAPI exception instance 
+        received from the DBAPI itself, *before* SQLAlchemy wraps the 
+        exception with it's own exception wrappers, and before any
+        other operations are performed on the DBAPI cursor; the
+        existing transaction remains in effect as well as any state
+        on the cursor.
+        
+        The use case here is to inject low-level exception handling
+        into an :class:`.Engine`, typically for logging and
+        debugging purposes.   In general, user code should **not** modify
+        any state or throw any exceptions here as this will
+        interfere with SQLAlchemy's cleanup and error handling
+        routines.
+        
+        Subsequent to this hook, SQLAlchemy may attempt any
+        number of operations on the connection/cursor, including
+        closing the cursor, rolling back of the transaction in the 
+        case of connectionless execution, and disposing of the entire
+        connection pool if a "disconnect" was detected.   The
+        exception is then wrapped in a SQLAlchemy DBAPI exception
+        wrapper and re-thrown.
+        
+        New in 0.7.7.
+
+        """
+
     def begin(self, conn):
         """Intercept begin() events."""