django-oscar-api 与 Django 的 UpdateCacheMiddleware 冲突：{TypeError}cannot pickle '_io.BufferedReader' object

Question

我使用 django-oscar-api 在 django-oscar 项目中实现了 django 的 per site cache。我使用 LocMemCache 作为缓存后端。

在将django.middleware.cache.UpdateCacheMiddleware 添加到我的中间件之前，一切正常，我可以像这样向“篮子”端点发出请求，它返回了 200 响应：

import requests

session = session.Session()
r_basket = session.get("http://127.0.0.1:8000/api/basket/")

添加每个站点缓存后，响应的状态代码为 500。我对其进行了调试，但它在 UpdateCacheMiddleware 中失败，并出现以下错误：{TypeError}cannot pickle '_io.BufferedReader' object。

其他端点似乎工作正常，但我还没有全部测试过。 该错误也可以在新安装的django-oscar sandbox 上重现。我 pip 安装了 django-oscar-api 并将其添加到已安装的应用程序中，MIDDLEWARE 设置如下所示：

MIDDLEWARE = [
    'debug_toolbar.middleware.DebugToolbarMiddleware',

    'django.middleware.security.SecurityMiddleware',
    'whitenoise.middleware.WhiteNoiseMiddleware',

    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.contrib.flatpages.middleware.FlatpageFallbackMiddleware',

    # Allow languages to be selected
    'django.middleware.locale.LocaleMiddleware',
    'django.middleware.http.ConditionalGetMiddleware',
    'django.middleware.common.CommonMiddleware',

    # per site caching
    'django.middleware.cache.UpdateCacheMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.cache.FetchFromCacheMiddleware',

    # Ensure a valid basket is added to the request instance for every request
    'oscar.apps.basket.middleware.BasketMiddleware',
]

我的包版本是 Django v.3.2.9、django-oscar v.2.2 或 3.0、django-oscar-api v.2.1.1。

什么东西不能腌制？还是中间件的顺序可能不对？

追溯：

[2021-11-13 08:43:33,256] Internal Server Error: /api/basket/
Traceback (most recent call last):
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/utils/deprecation.py", line 119, in __call__
    response = self.process_response(request, response)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/middleware/cache.py", line 111, in process_response
    response.add_post_render_callback(
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/template/response.py", line 92, in add_post_render_callback
    callback(self)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/middleware/cache.py", line 112, in <lambda>
    lambda r: self.cache.set(cache_key, r, timeout)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/debug_toolbar/panels/cache.py", line 39, in wrapped
    value = method(self, *args, **kwargs)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/debug_toolbar/panels/cache.py", line 94, in set
    return self.cache.set(*args, **kwargs)
  File "/home/victor/PycharmProjects/virtual_environments/django-oscar-sandbox/lib/python3.8/site-packages/django/core/cache/backends/locmem.py", line 56, in set
    pickled = pickle.dumps(value, self.pickle_protocol)
TypeError: cannot pickle '_io.BufferedReader' object

预期响应

{'id': 1,
 'owner': None,
 'status': 'Open',
 'lines': 'http://127.0.0.1:8000/api/baskets/1/lines/',
 'url': 'http://127.0.0.1:8000/api/baskets/1/',
 'total_excl_tax': '0.00',
 'total_excl_tax_excl_discounts': '0.00',
 'total_incl_tax': '0.00',
 'total_incl_tax_excl_discounts': '0.00',
 'total_tax': '0.00',
 'currency': None,
 'voucher_discounts': [],
 'offer_discounts': [],
 'is_tax_known': True}

查看：oscarapi.views.basket.BasketView

Answer 1

您需要确保 UpdateCacheMiddleware 在您的设置中位于 SessionMiddleware 和 LocaleMiddleware 之前。 DOCS

FetchFromCacheMiddleware 需要在那些中间件之后，可以留在原处

MIDDLEWARE = [
    'debug_toolbar.middleware.DebugToolbarMiddleware',

    'django.middleware.security.SecurityMiddleware',
    'whitenoise.middleware.WhiteNoiseMiddleware',

    # Moved UpdateCacheMiddleware to here
    'django.middleware.cache.UpdateCacheMiddleware',

    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.contrib.flatpages.middleware.FlatpageFallbackMiddleware',

    # Allow languages to be selected
    'django.middleware.locale.LocaleMiddleware',
    'django.middleware.http.ConditionalGetMiddleware',
    'django.middleware.common.CommonMiddleware',

    # per site caching
    'django.middleware.cache.FetchFromCacheMiddleware',

    # Ensure a valid basket is added to the request instance for every request
    'oscar.apps.basket.middleware.BasketMiddleware',
]