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Ticket #7967 (closed: fixed)

Opened 4 months ago

Last modified 4 months ago

cache.has_key() doesn't do the same thing as "key in cache"

Reported by: Gulopine Assigned to: Gulopine
Milestone: 1.0 Component: Core framework
Version: SVN Keywords:
Cc: Triage Stage: Unreviewed
Has patch: 1 Needs documentation: 0
Needs tests: 0 Patch needs improvement: 0

Description

In django.core.cache.backends.base.BaseCache, has_key() is defined as a method, while __contains__ is simply an alias for it. Individual backends override has_key() to be more efficient, but __contains__ is left alone, so it's still an alias for the base function, which unfortunately means that the two end up with different implementations. This is generally fine, but shows itself when None is stored in the cache, which is a potentially useful situation. 

>>> from django.core.cache import cache
>>> cache.set('test', None)
>>> cache.has_key('test')
True
>>> 'test' in cache
False

Attachments

7967-r8075.diff (1.5 kB) - added by Gulopine on 07/25/08 21:11:22.
Fixed __contains__ to always call has_key() and added tests to verify they work the same way.

Change History

07/25/08 21:11:22 changed by Gulopine

  • attachment 7967-r8075.diff added.

Fixed __contains__ to always call has_key() and added tests to verify they work the same way.

07/25/08 21:15:50 changed by Gulopine

  • needs_better_patch changed.
  • needs_tests changed.
  • needs_docs changed.

For what it's worth, I tested with with locmem, but since key in cache always calls BaseCache.__contains__, it actually doesn't matter what backend is used. There's also probably a case to be made that BaseCache.has_key() itself is buggy, since it could specify a default instead of assuming the default will always be None, but since all the backends override it, it's not a concern unless a custom backend (which is only recently possible) doesn't supply its own has_key().

07/25/08 22:58:32 changed by mtredinnick

  • status changed from new to closed.
  • resolution set to fixed.

(In [8084]) Fixed #7967 -- Make sure the contains method in the cache backends call the right has_key() method for the subclass. Patch from Marty Alchin.

Add/Change #7967 (cache.has_key() doesn't do the same thing as "key in cache")




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