| from django.contrib.messages.storage.base import BaseStorage |
| from django.contrib.messages.storage.cookie import CookieStorage |
| from django.contrib.messages.storage.session import SessionStorage |
| |
| class FallbackStorage(BaseStorage): |
| """ |
| Tries to store all messages in the first backend, storing any unstored |
| messages in each subsequent backend backend. |
| """ |
| storage_classes = (CookieStorage, SessionStorage) |
| |
| def __init__(self, *args, **kwargs): |
| super(FallbackStorage, self).__init__(*args, **kwargs) |
| self.storages = [storage_class(*args, **kwargs) |
| for storage_class in self.storage_classes] |
| self._used_storages = set() |
| |
| def _get(self, *args, **kwargs): |
| """ |
| Gets a single list of messages from all storage backends. |
| """ |
| all_messages = [] |
| for storage in self.storages: |
| messages, all_retrieved = storage._get() |
| # If the backend hasn't been used, no more retrieval is necessary. |
| if messages is None: |
| break |
| if messages: |
| self._used_storages.add(storage) |
| all_messages.extend(messages) |
| # If this storage class contained all the messages, no further |
| # retrieval is necessary |
| if all_retrieved: |
| break |
| return all_messages, all_retrieved |
| |
| def _store(self, messages, response, *args, **kwargs): |
| """ |
| Stores the messages, returning any unstored messages after trying all |
| backends. |
| |
| For each storage backend, any messages not stored are passed on to the |
| next backend. |
| """ |
| for storage in self.storages: |
| if messages: |
| messages = storage._store(messages, response, |
| remove_oldest=False) |
| # Even if there are no more messages, continue iterating to ensure |
| # storages which contained messages are flushed. |
| elif storage in self._used_storages: |
| storage._store([], response) |
| self._used_storages.remove(storage) |
| return messages |
