I have been writing scripts for a few weeks, and today I finally started to get in touch with web frameworks~ To learn Python’s web framework, Django is almost a required course. This time, I will start with it first. The main task is to Add the version number in the setting, attach the version number when rendering the path of static css and js, such as "example.v1124.css", and then remove the version number in the request request. Why do you do that? Because if you do this, the path to the static file output on the front end will be added with the version number. In this way, when a new static file is developed, the client will forcefully refresh the local cache. In order to achieve this purpose, you must first It must be configured in the settings file, so that the version number can be read directly from the settings every time it is modified.
1. Request cycle of Django middleware
We Send a request Request from the browser and get a response content HttpResponse. The process of passing this request to Django is as follows:
In other words, every request is first Through the process_request function in the middleware, this function returns None or HttpResponse object. If it returns the former, continue processing other middleware. If it returns an HttpResponse, the processing is aborted and returned to the web page.
2. Customize and register middleware
1. Create middleware
Create the middleware py file in the project root directory:
1 class RequestExeute(object): 2 def process_request(self, request): 3 print('process_request') 4 5 def process_view(self, request, callback, callback_args, callback_kwargs): 6 print('process_view') 7 8 def process_exception(self, request, exception): 9 """10 当views函数出错时执行11 :param request:
12 :param exception:
13 :return:
14 """15 print('process_exception')16 17 def process_response(self, request, response):18 """19 必须return HttpResponse20 :param request:
21 :param response:
22 :return:
23 """24 print('process_response')25 return response26 27 def process_template_response(self, request, response):28 """29 视图函数的返回值中，如果有render方法，才被调用30 :param request:31 :param response:32 :return:33 """34 print('process_template_response')35 return responseCopy after login
2. Register middleware
In the settings.py file, register in the order you want to execute ：
ps. In versions 1.9 and earlier, the keyword of middleware is: MIDDLEWARE_CLASSES
MIDDLEWARE_CLASSES = ('zqxt.middleware.BlockedIpMiddleware',
...其它的中间件
)Copy after login
3. Middle Execution sequence of methods in the file
1. Normal situation
1 from django.shortcuts import HttpResponse 2 from django.utils.deprecation import MiddlewareMixin 3 class M1(MiddlewareMixin): 4 def process_request(self, request): 5 print('m1.request') 6 # return HttpResponse('request_m1') 7 8 def process_view(self, request, callback, callback_args, callback_kwargs): 9 print('m1.view')10 # response = callback(request, *callback_args, **callback_kwargs)11 # return response12 13 def process_response(self, request, response):14 print('m1.response')15 return response16 17 def process_exception(self, request, exception):18 print('m1.process_exception')19 return HttpResponse('m1.process_exception')20 21 def process_template_response(self, request, response):22 """23 视图函数的返回值中，如果有render方法，才被调用24 :param request:25 :param response:26 :return:27 """28 print('m1.process_template_response')29 return response30 31 32 class M2(MiddlewareMixin):33 def process_request(self, request):34 print('m2.request')35 36 def process_view(self, request, callback, callback_args, callback_kwargs):37 print('m2.view')38 # response = callback(request, *callback_args, **callback_kwargs)39 # return response40 41 def process_response(self, request, response):42 print('m2.response')43 return response44 45 def process_exception(self, request, exception):46 print('m2.process_exception')47 return HttpResponse('m2.process_exception')48 49 def process_template_response(self, request, response):50 """51 视图函数的返回值中，如果有render方法，才被调用52 :param request:53 :param response:54 :return:55 """56 print('m2.process_template_response')57 return responseCopy after login
Execution order:
m1.request
m2.request
m1.view
m2.view
m2.response
m1.response
2. In version 1.10 and later
If process_request returns an HttpResponse object, return forward from the process_response of the current middleware
1 from django.shortcuts import HttpResponse 2 from django.utils.deprecation import MiddlewareMixin 3 class M1(MiddlewareMixin): 4 def process_request(self, request): 5 print('m1.request') 6 return HttpResponse('request_m1') 7 8 def process_view(self, request, callback, callback_args, callback_kwargs): 9 print('m1.view')10 # response = callback(request, *callback_args, **callback_kwargs)11 # return response12 13 def process_response(self, request, response):14 print('m1.response')15 return response16 17 def process_exception(self, request, exception):18 print('m1.process_exception')19 return HttpResponse('m1.process_exception')20 21 def process_template_response(self, request, response):22 """23 视图函数的返回值中，如果有render方法，才被调用24 :param request:25 :param response:26 :return:27 """28 print('m1.process_template_response')29 return response30 31 32 class M2(MiddlewareMixin):33 def process_request(self, request):34 print('m2.request')35 36 def process_view(self, request, callback, callback_args, callback_kwargs):37 print('m2.view')38 # response = callback(request, *callback_args, **callback_kwargs)39 # return response40 41 def process_response(self, request, response):42 print('m2.response')43 return response44 45 def process_exception(self, request, exception):46 print('m2.process_exception')47 return HttpResponse('m2.process_exception')48 49 def process_template_response(self, request, response):50 """51 视图函数的返回值中，如果有render方法，才被调用52 :param request:53 :param response:54 :return:55 """56 print('m2.process_template_response')57 return response58 59 60 # class RequestExeute(object):61 # def process_request(self, request):62 # print('process_request')63 #64 # def process_view(self, request, callback, callback_args, callback_kwargs):65 # print('process_view')66 #67 # def process_exception(self, request, exception):68 # """69 # 当views函数出错时执行70 # :param request:71 # :param exception:72 # :return:73 # """74 # print('process_exception')75 #76 # def process_response(self, request, response):77 # """78 # 必须return HttpResponse79 # :param request:80 # :param response:81 # :return:82 # """83 # print('process_response')84 # return response85 #86 # def process_template_response(self, request, response):87 # """88 # 视图函数的返回值中，如果有render方法，才被调用89 # :param request:90 # :param response:91 # :return:92 # """93 # print('process_template_response')94 # return responseCopy after login
Execution order:
m1.request
m1.response
process_view is similar to process_request:
1 from django.shortcuts import HttpResponse 2
from django.utils.deprecation import MiddlewareMixin 3 class M1(MiddlewareMixin): 4
def process_request(self, request): 5
print('m1.request') 6
# return HttpResponse('request_m1') 7 8
def process_view(self, request, callback, callback_args, callback_kwargs): 9
print('m1.view')10 response = callback(request, *callback_args, **callback_kwargs)11
return response12 13 def process_response(self, request, response):14 print('m1.response')15
return response16 17 def process_exception(self, request, exception):18
print('m1.process_exception')19
return HttpResponse('m1.process_exception')20 21 def process_template_response(self, request, response):22 """23 视图函数的返回值中，如果有render方法，才被调用24 :param request:25 :param response:26 :return:27 """28 print('m1.process_template_response')29 return response30 31 32 class M2(MiddlewareMixin):33 def process_request(self, request):34 print('m2.request')35 36 def process_view(self, request, callback, callback_args, callback_kwargs):37 print('m2.view')38 # response = callback(request, *callback_args, **callback_kwargs)39 # return response40 41 def process_response(self, request, response):42 print('m2.response')43 return response44 45 def process_exception(self, request, exception):46 print('m2.process_exception')47 return HttpResponse('m2.process_exception')48 49 def process_template_response(self, request, response):50 """51 视图函数的返回值中，如果有render方法，才被调用52 :param request:53 :param response:54 :return:55 """56 print('m2.process_template_response')57 return responseCopy after login
Execution order:
m1.request
m2.request
m1.view
m2.response
m1.respons
Copy after login
3. Before version 1.10
If process_request returns an HttpResponse object , then the process_request after the current middleware will not be executed, and the process_response of the last middleware will be returned forward
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