django遇到的那些古怪问题
2024-08-31 17:05:05
AssertionError: .accepted_renderer not set on Response
出错原因,没有在合法的方法内使用 response 响应,之前在dispatch内直接return 了,导致报错,return response 必须放在 get post 等方法内。
按道理讲,django视图会先经过dispatch分发,如果我们在分发的时候发现权限问题,那么提前响应应该没问题,那么为啥会报错呢?
报错信息显示accepted_renderer没有在Response内设定,找一下源码,如下(具体原因都在下面代码后面的注释里了):
def dispatch(self, request, *args, **kwargs):
"""
`.dispatch()` is pretty much the same as Django's regular dispatch,
but with extra hooks for startup, finalize, and exception handling.
"""
self.args = args
self.kwargs = kwargs
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate? try:
self.initial(request, *args, **kwargs) # Get the appropriate handler method
if request.method.lower() in self.http_method_names:
handler = getattr(self, request.method.lower(),
self.http_method_not_allowed)
else:
handler = self.http_method_not_allowed response = handler(request, *args, **kwargs) # 这里发现了,请求响应是在dispatch方法内部完成的,响应也是dispatch代为返回的,到这里也没问题,问题在下面。 except Exception as exc:
response = self.handle_exception(exc) self.response = self.finalize_response(request, response, *args, **kwargs) # 在响应之前,dispatch对视图方法返回的响应又加工了一次
return self.response def finalize_response(self, request, response, *args, **kwargs):
"""
Returns the final response object.
"""
# Make the error obvious if a proper response is not returned
assert isinstance(response, HttpResponseBase), (
'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` '
'to be returned from the view, but received a `%s`'
% type(response)
) if isinstance(response, Response):
if not getattr(request, 'accepted_renderer', None):
neg = self.perform_content_negotiation(request, force=True)
request.accepted_renderer, request.accepted_media_type = neg response.accepted_renderer = request.accepted_renderer # 这里,Response 会定义一个属性 accepted_renderer,也就是说,视图响应的不仅仅是一个 Response,而是加工过的Response,所以如果在dispatch内直接响应Response,就是跳过了后面加工哪一步,就会报错。
response.accepted_media_type = request.accepted_media_type
response.renderer_context = self.get_renderer_context() for key, value in self.headers.items():
response[key] = value return response
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
出错原因,两个,第一,相关包没有安装或者版本有问题;第二,在不合适的地方使用了项目的model模型,版本不同情况不一样。
XXX doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported
出错原因,在不合适的地方导用了model,如本次是在 app.__init__.py中导入本app的model导致的
虚拟环境中,Python库的安装直接使用pip安装,不用加sudo,不然项目没有权限使用该库,会导致出现 Apps aren't loaded yet.
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