在Django 1.3.1中使视图缓存失效

Question

我正在尝试使模型post_save上的视图级缓存失效（通过https://docs.djangoproject.com/en/1.3/topics/cache/?from=olddocs#the-per-view-cache设置）。我做了一些谷歌搜索，并在SO Expire a view-cache in Django?找到了这个答案，但它对我不起作用。

我在freenode的#django房间里问过，并且大家一致认为这可能是由于the recent caching changes made in 1.3

有没有人知道如何清除关键模型get_absolute_url()的缓存条目？

Answer 1

我想通了！

欢呼ilvar让我指向正确的方向。我的实现如下。我创建了一个名为cache_key的属性，并将一个post_save接收器添加到模型的子类中，这些模型的视图级缓存在更新后需要清除。欢迎提出改进建议！

from django.conf import settings
from django.core.cache import cache
from django.db.models.signals import post_save
from django.http import HttpRequest
from django.utils.cache import _generate_cache_header_key

from someapp.models import BaseModelofThisClass

class SomeModel(BaseModelofThisClass):
    ...
    @property
    def cache_key(self):
        # Create a fake request object
        request = HttpRequest()
        # Set the request method
        request.method = "GET"
        # Set the request path to be this object's permalink.
        request.path = self.get_absolute_url()
        # Grab the key prefix (if it exists) from settings
        key_prefix = settings.CACHE_MIDDLEWARE_KEY_PREFIX
        # Generate this object's cache key using django's key generator
        key = _generate_cache_header_key(key_prefix, request)
        # This is a bit hacky but necessary as I don't know how to do it
        # properly otherwise. While generating a cache header key, django
        # uses the language of the HttpRequest() object as part of the
        # string. The fake request object, by default, uses
        # settings.LANGUAGE_CODE as it's language (in my case, 'en-us')
        # while the true request objects that are used in building views
        # use settings.LANGUAGES ('en'). Instead of replacing the segment
        # of the string after the fact it would be far better create a more
        # closely mirrored HttpRequest() object prior to passing it to
        # _generate_cache_header_key().
        key = key.replace(settings.LANGUAGE_CODE, settings.LANGUAGES[settings.DEFAULT_LANGUAGE][0])

        return key

    @receiver(post_save)
    def clear_cache_for_this_item(sender, instance, **kwargs):
        # If this is a sub-class of another model
        if sender not in BaseModelofThisClass.__subclasses__():
            return
        else:
            cache.delete(instance.cache_key)

Answer 2

Django的缓存中间件正在使用this为请求生成缓存密钥。因此，您可以使用所需路径制作假request并获取缓存密钥。然后只需将其从缓存中删除即可。

P.S。 cache_page装饰器也使用那些中间件，所以它应该以相同的方式工作。