from django.db import connection, transaction


class TransactionMiddleware(object):
    """
    Transaction middleware. If this is enabled, each view function will be run
    with commit_on_response activated - that way a save() doesn't do a direct
    commit, the commit is done when a successful response is created. If an
    exception happens, the database is rolled back.
    """
    pass
#    def process_request(self, request):
#        """Enters transaction management"""
#        transaction.enter_transaction_management()
#    
#    def process_exception(self, request, exception):
#        """Rolls back the database and leaves transaction management"""
#        if transaction.is_dirty():
#            # This rollback might fail because of network failure for example.
#            # If rollback isn't possible it is impossible to clean the
#            # connection's state. So leave the connection in dirty state and
#            # let request_finished signal deal with cleaning the connection.
#            transaction.rollback()
#        transaction.leave_transaction_management()
#    
#    def process_response(self, request, response):
#        """Commits and leaves transaction management."""
#        if not transaction.get_autocommit():
#            if transaction.is_dirty():
#                # Note: it is possible that the commit fails. If the reason is
#                # closed connection or some similar reason, then there is
#                # little hope to proceed nicely. However, in some cases (
#                # deferred foreign key checks for exampl) it is still possible
#                # to rollback().
#                try:
#                    transaction.commit()
#                except Exception:
#                    # If the rollback fails, the transaction state will be
#                    # messed up. It doesn't matter, the connection will be set
#                    # to clean state after the request finishes. And, we can't
#                    # clean the state here properly even if we wanted to, the
#                    # connection is in transaction but we can't rollback...
#                    transaction.rollback()
#                    transaction.leave_transaction_management()
#                    raise
#            transaction.leave_transaction_management()
#        return response