How to match redis key patterns using native django cache?

Question

I have a series of caches which follow this pattern:

key_x_y = value

Like:

  'key_1_3' = 'foo'
  'key_2_5' = 'bar'
  'key_1_7' = 'baz'

Now I'm wondering how can I iterate over all keys to match pattern like key_1_* to get foo and baz using the native django cache.get()?

(I know that there are way, particularly for redis, that allow using more extensive api like iterate, but I'd like to stick to vanilla django cache, if possible)

Answer 1

This is not possible using standard Django's cache wrapper. As the feature to search keys by pattern is a backend dependent operation and not supported by all the cache backends used by Django (e.g. memcached does not support it but Redis does). So you will have to use a custom cache wrapper with cache backend that supports this operation.

Edit: If you are already using django-redis then you can do

from django.core.cache import cache
cache.keys("foo_*")

as explained here.

This will return list of keys matching the pattern then you can use cache.get_many() to get values for these keys.

cache.get_many(cache.keys("key_1_*"))

Answer 2

If the cache has following entries:

cache = {'key_1_3': 'foo', 'key_2_5': 'bar', 'key_1_7': 'baz'}

You can get all the entries which has key key_1_*:

x = {k: v for k, v in cache.items() if k.startswith('key_1')}

---

Based on the documentation from django-redis

You can list all the keys with a pattern:

>>> from django.core.cache import cache
>>> cache.keys("key_1_*")
# ["key_1_3", "key_1_7"]

once you have the keys you can get the values from this:

>>> [cache.get(k) for k in cache.keys("key_1_*")]
# ['foo', 'baz']

You can also use cache.iter_keys(pattern) for efficient implementation.

Or, as suggested by @Muhammad Tahir, you can use cache.get_many(cache.keys("key_1_*")) to get all the values in one go.