django8-django的中间件
1.django的客户请求流程
之前登录功能 ,需要获取用户的sesssion ,但是每个视图函数都要加装饰器来校验很不合理 ,中间件就可以解决这个问题
用户客户端--->wsgi(封装了request对象)--->中间件(框架hook)--->路由--->views--->models--->db--->template---中间件--->wsgi--->客户端
2.什么是中间件
django中间件用来处理django的请求和响应框架级别的钩子 ,在全局范围内改变django的输入和输出 ,有多种类型中间件, 每个中间件都可以完成特定功能 ,可以帮助我们在执行视图函数前后完成额外操作 ,本质是类
settings中MIDDLEWARE配置的就是中间件信息 ,字符串也是一个个类 ,也就是一个个中间件 ,可以通过import点击查看类
3.自定义中间件
5种中间件 ,关注点在于 参数! 执行的时机! 执行顺序! 返回值!
本质就是类 ,类中定义下前面的五种方法 ,在不同时机执行产生不同作用!
process_request(self,request)
process_view(self,request,view_func,view_args,view_kwargs)
process_template_response(self,request,response)
process_exception(self,request,exception)
process_response(self,request,response)
1)process_request(self,request)
参数: wsgi返回的request对象
执行时间: 在收到request后执行之前 (截断不满足要求的请求)
执行顺序: 按照setting注册顺序执行 ,在注册的类中按顺序拿出每个类中这个方法执行
返回值:
当返回值为空None: url-->views
当返回response对象: 直接返回客户端
##middle/middles.py 一个类就是一个中间件 ,可以写多个 from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse class MD1(MiddlewareMixin): def process_request(self, request): print('MD1 process_request') # return HttpResponse('拒绝访问') #如果return那么就会直接返回客户端 ##settings.py注册 MIDDLEWARE = [ ... 'middle.middles.MD1', ... ]
2)process_response(self,request,response)
参数: wsgi返回的request对象 ,response对象(可能是视图函数返回的 ,也可能是process_request返回的)
执行时机: 在视图函数执行之后 ,还可能是是process_request有返回值之后按顺序执行
执行顺序: 按照setting注册顺序倒序执行 ,在注册的类中倒叙获取每个类中的process_response方法执行
返回值: 必须返回response对象
##/middle/middles.py 写两个中间件查看执行顺序 from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse class MD1(MiddlewareMixin): def process_request(self, request): print('MD1 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD1 process_response') # return HttpResponse('拒绝访问') return response class MD2(MiddlewareMixin): def process_request(self, request): print('MD2 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD2 process_response') # return HttpResponse('拒绝访问') return response ##settings 注册两个中间件类 MIDDLEWARE = [ ... 'middle.middles.MD1', 'middle.middles.MD2', ... ]
3)process_view(self,request,view_func ,view_args, view_kwargs)
参数: wsgi给的request对象 ,view_func匹配本次执行视图函数 ,view_args匹配本次视图函数位置参数 ,view_kwargs匹配本次视图函数关键字参数
执行时机: 在url匹配到视图函数后执行 ,再执行视图函数
执行顺序: 按照setting注册顺序执行
返回值:
返回值为空: 正常流程(process_request--->url--->process_view--->views.py--->process_response)
response对象: 截断流程(process_request--->url--->process_view(直接跳过所有view方法,和所有视图函数直接返回response)-->process_response)
##middle/middles.py 有返回值的view ,观察执行结果 from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse class MD1(MiddlewareMixin): def process_request(self, request): print('MD1 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD1 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD1 process_view', view_func) return HttpResponse('test') class MD2(MiddlewareMixin): def process_request(self, request): print('MD2 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD2 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD2 process_view', view_func) ###执行结果 MD1 process_request MD2 process_request MD1 process_view <function presslist at 0x0408BF60> #MD1有return ,MD2的view就不执行了直接跳到response MD2 process_response MD1 process_response
4)process_exception(self ,request, exception)
参数: wsgi返回的request对象 ,exception视图函数的异常
执行时机: 在执行视图函数 ,有异常的情况
执行顺序: 按setting的注册倒序执行
返回值:
返回值为空: 交给下一个process_exception处理
返回response对象: 跳过其他process_exception ,开始process_response的倒叙顺序执行 (如果所有的exception都没处理这个异常 ,那么最后会由django做异常处理)
from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse class MD1(MiddlewareMixin): def process_request(self, request): print('MD1 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD1 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD1 process_view', view_func) def process_exception(self, request, exception): print('MD1 process_exception') print(exception) return HttpResponse(exception) class MD2(MiddlewareMixin): def process_request(self, request): print('MD2 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD2 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD2 process_view') def process_exception(self, request, exception): print('MD2 process_exception') print(exception)
###视图函数中加入一条错误 ,让process_exception捕获 ,
MD1 process_request
MD2 process_request
MD1 process_view <function presslist at 0x03BAC078>
MD2 process_view
MD2 process_exception
invalid literal for int() with base 10: 'ok'
MD1 process_exception
invalid literal for int() with base 10: 'ok'
MD2 process_response
MD1 process_response
5)process_template_response(self,request,response)
参数: wsgi返回的request对象
执行时机: 视图函数执行返回Templateresponse对象才会执行
执行顺序: 根据setting注册顺序倒序执行 ,如果设置了多个该类型中间件结果会是最后一个
返回值: response对象(Templateresponse对象)
Templateresponse对象: 这个对象使用与render相似 ,但是render最终返回的也是Httpresponse对象 ! 目前两个对象区别就在于templateresponse可以在中间件进行修改
from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse class MD1(MiddlewareMixin): def process_request(self, request): print('MD1 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD1 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD1 process_view', view_func) def process_exception(self, request, exception): print('MD1 process_exception') print(exception) return HttpResponse(exception) def process_template_response(self, request, response): response.context_data = {'author': 'ggg'} print('MD1 process_template_response') return response ##middle/middles.py 指定templateresponse返回的数据 class MD2(MiddlewareMixin): def process_request(self, request): print('MD2 process_request') # return HttpResponse('拒绝访问') def process_response(self, request, response): print('MD2 process_response') # return HttpResponse('拒绝访问') return response def process_view(self, request, view_func, view_args, view_kwargs): print('MD2 process_view') def process_exception(self, request, exception): print('MD2 process_exception') print(exception) def process_template_response(self, request, response): response.context_data = {'author': '7777'} print('MD2 process_template_response') return response ##视图函数返回编程templateresponse对象 from django.template.response import TemplateResponse def presslist(request): msg_all = models.presslist.objects.all() return TemplateResponse(request, 'cbs.html', {'msg': msg_all, 'author': 'qgw'})
5.session使用中间件优化
将校验的session的过程放到process_request中
1.如果客户端没有cookie存储的sessionid则跳转到login函数
2.如果用户访问login函数那么就不需要cookie
from django.utils.deprecation import MiddlewareMixin from django.shortcuts import render, HttpResponse, reverse, redirect, HttpResponseRedirect class MD1(MiddlewareMixin): """缺陷是如果login函数能跳过中间件就好了""" def process_request(self, request): if not request.session.get('auth') and request.path_info != reverse('tlogin'): nowurl = request.path_info url = reverse('tlogin') + '?next={}'.format(nowurl) if nowurl == reverse('tlogin'): url = reverse('tlogin') return redirect(url)
解析csrf安全的中间件
