django caching pattern examples

mymodel.py

from django.core.cache import cache
from django.db import models

EMPTY = '-'  # Not "None"

class MyModel(models.Model):
    @classmethod
    def _cache_key(cls, key):
        return 'mymodel:{}'.format(key)
        
    @classmethod
    def get(cls, key):
        cache_key = cls._cache_key(key)
        obj = cache.get(cache_key)
        if obj == EMPTY:
            return None  # or raise DoesNotExist
        if obj:
            return obj
        try:
            obj = cls.objects.get(pk=key)
        except cls.DoesNotExist:
            cache.add(cache_key, EMPTY)
            return None  # or raise
        cache.add(cache_key, obj)
        return obj

    @classmethod
    def flush(cls, key):
        cache_key = cls._cache_key(key)
        cache.delete(cache_key)  # Can also "delete_many"

    def save(self, *args, **kwargs):
        ret = super(MyModel, self).save(*args, **kwargs)
        self.flush(self.pk)
        return ret

    def delete(self, *args, **kwargs):
        ret = super(MyModel, self).delete(*args, **kwargs)
        self.flush(self.pk)
        return ret

mymodeloptions.py

MyModelOptions._get_cache_key(cls, mymodel)
MyModelOptions.get(cls, mymodel)
MyModelOptions.flush(cls, mymodel)
MyModelOptions.save(self) (call flush)