mirror of
https://github.com/jazzband/django-constance.git
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e1f9e52a08
Drop python 2.6, 3.2 Drop Django 1.4, 1.5, 1.6 Remove models.py under constance and move to an appconfig imported file.
90 lines
3.3 KiB
Python
90 lines
3.3 KiB
Python
from django.core.cache.backends.locmem import LocMemCache
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from django.core.exceptions import ImproperlyConfigured
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from django.db.models.signals import post_save
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from django.core.cache import caches
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from .. import Backend
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from ... import settings
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class DatabaseBackend(Backend):
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def __init__(self):
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from .models import Constance
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self._model = Constance
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self._prefix = settings.DATABASE_PREFIX
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self._autofill_timeout = settings.DATABASE_CACHE_AUTOFILL_TIMEOUT
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self._autofill_cachekey = 'autofilled'
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if not self._model._meta.installed:
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raise ImproperlyConfigured(
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"The constance.backends.database app isn't installed "
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"correctly. Make sure it's in your INSTALLED_APPS setting.")
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if settings.DATABASE_CACHE_BACKEND:
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self._cache = caches[settings.DATABASE_CACHE_BACKEND]
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if isinstance(self._cache, LocMemCache):
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raise ImproperlyConfigured(
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"The CONSTANCE_DATABASE_CACHE_BACKEND setting refers to a "
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"subclass of Django's local-memory backend (%r). Please set "
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"it to a backend that supports cross-process caching."
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% settings.DATABASE_CACHE_BACKEND)
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else:
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self._cache = None
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self.autofill()
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# Clear simple cache.
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post_save.connect(self.clear, sender=self._model)
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def add_prefix(self, key):
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return "%s%s" % (self._prefix, key)
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def autofill(self):
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if not self._autofill_timeout or not self._cache:
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return
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full_cachekey = self.add_prefix(self._autofill_cachekey)
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if self._cache.get(full_cachekey):
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return
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autofill_values = {}
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autofill_values[full_cachekey] = 1
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for key, value in self.mget(settings.CONFIG.keys()):
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autofill_values[self.add_prefix(key)] = value
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self._cache.set_many(autofill_values, timeout=self._autofill_timeout)
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def mget(self, keys):
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if not keys:
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return
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keys = dict((self.add_prefix(key), key) for key in keys)
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stored = self._model._default_manager.filter(key__in=keys.keys())
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for const in stored:
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yield keys[const.key], const.value
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def get(self, key):
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key = self.add_prefix(key)
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if self._cache:
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value = self._cache.get(key)
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else:
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value = None
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if value is None:
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try:
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value = self._model._default_manager.get(key=key).value
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except self._model.DoesNotExist:
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pass
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else:
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if self._cache:
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self._cache.add(key, value)
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return value
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def set(self, key, value):
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constance, created = self._model._default_manager.get_or_create(
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key=self.add_prefix(key), defaults={'value': value}
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)
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if not created:
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constance.value = value
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constance.save()
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def clear(self, sender, instance, created, **kwargs):
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if self._cache and not created:
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keys = [self.add_prefix(k)
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for k in settings.CONFIG.keys()]
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keys.append(self.add_prefix(self._autofill_cachekey))
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self._cache.delete_many(keys)
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self.autofill()
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