django之中间件

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django中间件

跨站请求伪造

中间件的执行顺序从上往下的读

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MIDDLEWARE = [   # 从上往下的读
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    # 'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'app01.mymiddelware.MyMiddleware1',# 
    'app01.mymiddelware.MyMiddleware2',
]

新建一个文件middleware.py

与这个文件代码顺序无关

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from django.utils.deprecation import MiddlewareMixin

class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------2------->')

class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------1------->')

process_request 执行顺序从上往下

请求来的时候,会响应它

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http://127.0.0.1:8000/test_middle/?name=shouyue 
输入这个网站 用GET提取shouyue
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from django.utils.deprecation import MiddlewareMixin

class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print(request.GET.get('name'))
        print('MyMiddleware--------2------->')

class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------1------->')

process_response 执行顺序从下往上

响应回去的时候,会走它

错误示范

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from django.utils.deprecation import MiddlewareMixin
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):
        print('MyMiddleware--------response2------->')
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')
    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')

报错

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if response.get('X-Frame-Options') is not None:
AttributeError: 'NoneType' object has no attribute 'get'
[13/Jan/2021 15:03:22] "GET /test_middle/?name=shouyue HTTP/1.1" 500 58271

原因

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# wiews.py文件第一次返回响应
def test_middle(request):
    print('我是视图函数')
    return HttpResponse('I am view')
# middleware.py文件第二次返回响应process_response没有写返回HttpResponse对象或者返回None
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):
        print('MyMiddleware--------response2------->')
# middleware.py文件第三次返回响应process_response没有写返回HttpResponse对象或者返回None
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')
    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')

正确方案

需要在process_response写return response

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print(request.GET.get('name'))
        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')
        return response
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')

    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

将响应里面加cookie

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print(request.GET.get('name'))
        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')
        # 这样所有的响应都带有cookie
        response.set_cookie('name','shouyue')
        return response
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')

    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

流程图

image-20210113152832838

有意思的事情来了

测试一MyMiddleware1中间件

MyMiddleware2和视图函数被过滤掉了

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):

        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')
        # 这样所有的响应都带有cookie
        response.set_cookie('name','shouyue')
        return response
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')
        return HttpResponse('I am middle---1')
    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

测试二MyMiddleware1中间件 process_request返回的默认是None

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):

        print('MyMiddleware--------request2------->')
    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')
        # 这样所有的响应都带有cookie
        response.set_cookie('name','shouyue')
        return response
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')
        # 返回的是HttpResponse对象，直接返回，走自己的process_response
        # 返回None的时候，继续往下走
        return None
    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

结果

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MyMiddleware--------request1------->
MyMiddleware--------response1------->

测试三MyMiddleware2中间件

视图函数被过滤掉了

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):

        print('MyMiddleware--------request2------->')
        return HttpResponse('I am Middle2')
    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')
        # 这样所有的响应都带有cookie
        # response.set_cookie('name','shouyue')
        return HttpResponse('')
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')
        # 返回的是HttpResponse对象，直接返回，走自己的process_response
        # 返回None的时候，继续往下走
        return None
    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

结果

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MyMiddleware--------request1------->
MyMiddleware--------request2------->
MyMiddleware--------response2------->
MyMiddleware--------response1------->

process_view

request, callback(视图函数), callback_args(无名分组的参数), callback_kwargs(有名分组的参数)

流程图

image-20210113163552150

测试跳过MyMiddleware2的process_view

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):

        print('MyMiddleware--------request2------->')
    def process_view(self,request,callback,callback_args,callback_kwargs):
        print(callback)
        print(callback_args)
        print(callback_kwargs)
        ret=callback(request)
        return ret

    def process_response(self,request,response):

        print('MyMiddleware--------response2------->')

        return response
class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')



    def process_view(self,request,callback,callback_args,callback_kwargs):
        print(callback)
        print(callback_args)
        print(callback_kwargs)
        ret=callback(request)
        return ret


    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

作用

捕获异常直接返回

将视图函数写一个异常

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from django.shortcuts import render,HttpResponse

# Create your views here.

def test_middle(request):
    print('我是视图函数')
    a
    return HttpResponse('I am view')

middleware.py的process_exception

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request2------->')

    def process_response(self,request,response):
        print('MyMiddleware--------response2------->')
        return response

class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')

    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

    def process_exception(self,request,exception):
        print('middle---1----exception')
        print(exception)
        return HttpResponse(exception)

流程

image-20210113184551708

def process_exception(self, request, exception)(了解)
def process_template_response(self, request, response):(了解)

process_template_response

作用自动调用返回对象的render方法

views.py

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class Test():

    def render(self):
        return HttpResponse('test')

def test_middle(request):

    return Test()

middleware.py的process_template_response

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from django.utils.deprecation import MiddlewareMixin
from django.shortcuts import render,HttpResponse
class MyMiddleware2(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request2------->')


    def process_response(self,request,response):
        print('MyMiddleware--------response2------->')
        return response

class MyMiddleware1(MiddlewareMixin):
    def process_request(self,request):
        print('MyMiddleware--------request1------->')

    def process_response(self, request, response):
        print('MyMiddleware--------response1------->')
        return response

    def process_template_response(self, request, response):
        print('process_template_response')
        return response
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