import json from django.contrib.messages.storage.base import BaseStorage from django.contrib.messages.storage.cookie import MessageDecoder, MessageEncoder from django.core.exceptions import ImproperlyConfigured class SessionStorage(BaseStorage): """ Store messages in the session (that is, django.contrib.sessions). """ session_key = "_messages" def __init__(self, request, *args, **kwargs): if not hasattr(request, "session"): raise ImproperlyConfigured( "The session-based temporary message storage requires session " "middleware to be installed, and come before the message " "middleware in the MIDDLEWARE list." ) super().__init__(request, *args, **kwargs) def _get(self, *args, **kwargs): """ Retrieve a list of messages from the request's session. This storage always stores everything it is given, so return True for the all_retrieved flag. """ return ( self.deserialize_messages(self.request.session.get(self.session_key)), True, ) def _store(self, messages, response, *args, **kwargs): """ Store a list of messages to the request's session. """ if messages: self.request.session[self.session_key] = self.serialize_messages(messages) else: self.request.session.pop(self.session_key, None) return [] def serialize_messages(self, messages): encoder = MessageEncoder() return encoder.encode(messages) def deserialize_messages(self, data): if data and isinstance(data, str): return json.loads(data, cls=MessageDecoder) return data