Django进阶-middleware(中间件)

middleware （中间件）

是一个完整socket请求过程中必须经过的步骤   客户端发起request--->中间件request--->views处理--->中间件response--->客户端
   如果在中间件中请求出错，则直接返回响应
作用：可以对所有请求做统一操作，也可以进行过滤

中间件的5个方法：

process_request

process_view

process_exception

process_exception

process_template_response

# 接收请求后首先经过process_request
def process_request(self, request):
　　print('请求1')
　　pass

# 当process_request处理完后，进行路由映射，再返回第一条继续进行处理
def process_view(self, request, callback, callback_args, callback_kwargs):
　　pass

# 当views处理完，且其中有错时，就会自动调用此方法，可返回给页面错误信息（没有错就不执行）（执行顺序是倒序，
# 但如果和views最近的没有进行处理则往上查，查到后处理并返回最后一条进行process_response）

def process_exception(self, request, exception):
    return HttpResponse('页面出错了！！！')

# 当views处理完成之后倒序的进行返回，所以必须要有return response
def process_response(self, request, response):
    return response

# 如若views返回的内容中有render方法，则会执行
def process_template_response(self, request, response):

MIDDLEWARE = [
    # 'django.middleware.cache.UpdateCacheMiddleware',
    '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',
    'Middle.m1.Row1',
    'Middle.m1.Row2',
    'Middle.m1.Row3',
    # 'django.middleware.cache.FetchFromCacheMiddleware',
]

from django.middleware.csrf import CsrfViewMiddleware
from django.shortcuts import render,HttpResponse

# from sg import pizza_done
# pizza_done.send(sender='seven',toppings=123, size=456)  # 写在需要触发的位置


class Row1(CsrfViewMiddleware):
    def process_request(self, request):
        pass
        print('请求...1')
    def process_view(self, request, callback, callback_args, callback_kwargs):
        # pass
        print('请求...4')
    def process_response(self, request, response):
        print('响应3')
        return response
class Row2(CsrfViewMiddleware):
    def process_request(self, request):
        # pass
        print('请求...2')
    def process_view(self, request, callback, callback_args, callback_kwargs):
        # pass
        print('请求...5')
    def process_response(self, request, response):
        print('响应2')
        return response
class Row3(CsrfViewMiddleware):
    def process_request(self, request):
        # pass
        print('请求...3')
    def process_view(self, request, callback, callback_args, callback_kwargs):
        # pass
        print('请求...6')
    def process_response(self, request, response):
        print('响应1')
        return response
    def process_exception(self, request, exception):
        # pass
        print(exception)
        return HttpResponse(exception)