mirror of
https://github.com/Hopiu/django-imagekit.git
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60 lines
1.9 KiB
Python
60 lines
1.9 KiB
Python
from django.core.exceptions import ImproperlyConfigured
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from django.utils.importlib import import_module
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class PessimisticCacheStateBackend(object):
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"""
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A very safe cache state backend. Guarantees that files will always be
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available, but at the cost of hitting the storage backend.
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"""
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def is_invalid(self, file):
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if not getattr(file, '_file', None):
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# No file on object. Have to check storage.
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return not file.storage.exists(file.name)
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return False
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def validate(self, file):
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"""
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Generates a new image by running the processors on the source file.
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"""
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if self.is_invalid(file):
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file.generate(save=True)
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def invalidate(self, file):
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file.delete(save=False)
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def clear(self, file):
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file.delete(save=False)
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_default_cache_state_backend = None
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def get_default_cache_state_backend():
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"""
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Get the default cache state backend. Uses the same method as
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django.core.file.storage.get_storage_class
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"""
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global _default_cache_state_backend
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if not _default_cache_state_backend:
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from ..settings import DEFAULT_CACHE_STATE_BACKEND as import_path
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try:
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dot = import_path.rindex('.')
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except ValueError:
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raise ImproperlyConfigured("%s isn't a cache state backend module." % \
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import_path)
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module, classname = import_path[:dot], import_path[dot+1:]
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try:
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mod = import_module(module)
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except ImportError, e:
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raise ImproperlyConfigured('Error importing cache state module %s: "%s"' % (module, e))
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try:
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cls = getattr(mod, classname)
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_default_cache_state_backend = cls()
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except AttributeError:
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raise ImproperlyConfigured('Cache state backend module "%s" does not define a "%s" class.' % (module, classname))
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return _default_cache_state_backend
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