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1 from django.contrib.messages.storage.base import BaseStorage |
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2 from django.contrib.messages.storage.cookie import CookieStorage |
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3 from django.contrib.messages.storage.session import SessionStorage |
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4 |
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5 class FallbackStorage(BaseStorage): |
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6 """ |
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7 Tries to store all messages in the first backend, storing any unstored |
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8 messages in each subsequent backend backend. |
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9 """ |
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10 storage_classes = (CookieStorage, SessionStorage) |
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11 |
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12 def __init__(self, *args, **kwargs): |
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13 super(FallbackStorage, self).__init__(*args, **kwargs) |
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14 self.storages = [storage_class(*args, **kwargs) |
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15 for storage_class in self.storage_classes] |
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16 self._used_storages = set() |
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17 |
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18 def _get(self, *args, **kwargs): |
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19 """ |
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20 Gets a single list of messages from all storage backends. |
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21 """ |
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22 all_messages = [] |
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23 for storage in self.storages: |
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24 messages, all_retrieved = storage._get() |
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25 # If the backend hasn't been used, no more retrieval is necessary. |
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26 if messages is None: |
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27 break |
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28 if messages: |
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29 self._used_storages.add(storage) |
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30 all_messages.extend(messages) |
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31 # If this storage class contained all the messages, no further |
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32 # retrieval is necessary |
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33 if all_retrieved: |
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34 break |
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35 return all_messages, all_retrieved |
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36 |
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37 def _store(self, messages, response, *args, **kwargs): |
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38 """ |
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39 Stores the messages, returning any unstored messages after trying all |
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40 backends. |
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41 |
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42 For each storage backend, any messages not stored are passed on to the |
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43 next backend. |
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44 """ |
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45 for storage in self.storages: |
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46 if messages: |
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47 messages = storage._store(messages, response, |
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48 remove_oldest=False) |
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49 # Even if there are no more messages, continue iterating to ensure |
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50 # storages which contained messages are flushed. |
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51 elif storage in self._used_storages: |
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52 storage._store([], response) |
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53 self._used_storages.remove(storage) |
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54 return messages |