Redis cache backend doesn't allow storing bool values

[Jeremy Lainé]

The following code raises an exception: redis.exceptions.DataError: Invalid input of type: 'bool'. Convert to a bytes, string, int or float first.

from django.core.cache import cache
cache.set("foo", True)

This contradicts the documentation which states that any data type supported by pickle can be stored to the cache.

The root cause seems to be because instances of int are special-cased and not send through pickle, but redis-py cannot send booleans to redis:

​https://github.com/django/django/blob/2f73e5406d54cb8945e187eff302a3a3373350be/django/core/cache/backends/redis.py#L14

What was the rationale behind the int special-case? django-redis for instance consistently sends all data through pickle.

[Mariusz Felisiak]

Thanks for report! It should be enough to special-case bool, e.g.

django/core/cache/backends/redis.py

@@ -11 +11 @@
 
 class RedisSerializer(PickleSerializer):
     def dumps(self, obj):
-        if isinstance(obj, int):
+        if isinstance(obj, int) and not isinstance(obj, bool):
             return obj
         return super().dumps(obj)
 

Would you like to prepare a patch?

What was the rationale behind the int special-case? django-redis for instance consistently sends all data through pickle.

We do this to have better atomicity of incr() and decr() operations (see ​discussion).