1 from django.conf import settings

     2 from django.contrib.messages.storage import default_storage

     3 

     4 

     5 class MessageMiddleware(object):

     6     """

     7     Middleware that handles temporary messages.

     8     """

     9 

    10     def process_request(self, request):

    11         request._messages = default_storage(request)

    12 

    13     def process_response(self, request, response):

    14         """

    15         Updates the storage backend (i.e., saves the messages).

    16 

    17         If not all messages could not be stored and ``DEBUG`` is ``True``, a

    18         ``ValueError`` is raised.

    19         """

    20         # A higher middleware layer may return a request which does not contain

    21         # messages storage, so make no assumption that it will be there.

    22         if hasattr(request, '_messages'):

    23             unstored_messages = request._messages.update(response)

    24             if unstored_messages and settings.DEBUG:

    25                 raise ValueError('Not all temporary messages could be stored.')

    26         return response