Allow CACHES['cache']['TIMEOUT']: None to set a non-expiring timeout by default.

[honi]

BaseCache will try to cast the default timeout to int, which will throw a TypeError if timeout is None, thus setting default_timeout to 300.

Relevant lines here: ​https://github.com/django/django/blob/master/django/core/cache/backends/base.py#L54-L59

Django 1.6 made some changes to allow setting the cache timeout to None for non expiring keys, as described here: ​https://github.com/django/django/blob/master/django/core/cache/backends/base.py#L54-L59

Explicitly passing None in cache.set works as expected. It does not work if set in CACHE dict in django settings.

This currently does not work for me (keys expire in 300 seconds):

CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
        'LOCATION': 'unique-snowflake',
        'TIMEOUT': None
    }
}

[Tim Graham]

This is outside of the scope of the changes in Django 1.6 so it's really more of a feature request than a bug.

[Rigel Di Scala]

I have implemented this feature and written several tests for it.

The pull request is here: ​https://github.com/django/django/pull/2365

[Tim Graham]

The patch needs to include an update to the documentation and a mention in the release notes.

[Baptiste Mispelon <bmispelon@…>]

In 6fe22b30e007b7ac49eae48a53e7ba0a4ee79a4b:

Fixed #22085 -- Added a feature for setting non-expiring keys as the default.

This feature allows the default TIMEOUT Cache argument to be set to None,
so that cache instances can set a non-expiring key as the default,
instead of using the default value of 5 minutes.

Previously, this was possible only by passing None as an argument to
the set() method of objects of type BaseCache (and subtypes).