python---django请求-响应的生命周期（FBV和CBV含义）

时间：2023-01-08 08:33:36

Django请求的生命周期是指：当用户在访问该url路径是，在服务器Django后台都发生了什么。

客户端发送Http请求给服务端，Http请求是一堆字符串,其内容是：python---django请求-响应的生命周期（FBV和CBV含义）

访问：http://crm.oldboy.com:8080/login.html，客户端发送Http请求

1.路由映射，匹配路由（从上到下，匹配到就停止），对应相应views中的业务函数

url(r'^login.html', views.login),

2.匹配成功后，执行views下的对应函数：（FBV）

def login(req):

    print('req.body',req.body)

    print("GET",req.GET)

    message=''

    if req.method == "POST":

        print(req.body)

        print(req.POST)

        user = req.POST.get("username")

        pwd = req.POST.get("password")

        count = models.Administrator.objects.filter(username=user,password=pwd).count()

        if count:

            red = redirect("/index.html")

            timeout = datetime.datetime.now()+datetime.timedelta(seconds=)

            red.set_cookie('username',user,expires=timeout)

            return red

        else:

            message = "用户名或密码错误"

    return render(req,"login.html",{'msg':message})
URL -->  函数  ====>  FBV(Function-based views)    基于函数的视图
URL -->  类    ====> CBV (Class-based views)    基于类的视图

FBV：在Django中使用较多，在其他框架中多使用CBV，例如tornado,还有PHP的多种框架等

Django中CBV使用：

首先需要设置views中的类：

from django.views import View

class CBV(View):
　　 #根据请求头中的request method进行自动执行get和post

    def get(self,request):

        return render(request,"cbv_login.html")

    def post(self,request):

        return HttpResponse("<h1>cbv_post</h1>")

然后修改urls文件路由：

urlpatterns = [

    url(r"cbv",views.CBV.as_view())

]

模板文件：

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<form action="/cbv" method="post">

    {% csrf_token %}

    <div>

        <label for="user">用户名：</label>

        <input type="text" id="user" name="username"/>

    </div>

    <div>

        <label for="pwd">密码：</label>

        <input type="password" id="pwd" name="password"/>

    </div>

    <div>

        <label></label>

        <input type="submit" value="登录">

        <label>{{ msg }}</label>

    </div>

</form>

</body>

</html>

cbv_login.html

使用url访问默认是get方式，显示cbv_login.html页面，提交页面，进入post页面，显示cbv_post数据

get还是post，是由于请求头中的Request Method:获取，从而找到对应方法。使用反射查找，来执行对应方法。

.由Request URL请求去获取路径，与urls进行匹配，找到对应的类

.由请求体得到：Request Method：GET

.获得类中方法

   方法名  =  getattr(对象，"GET")

   方法名()    #执行对应函数

源码查看：

@classonlymethod

    def as_view(cls, **initkwargs):

        """

        Main entry point for a request-response process.请求-响应的主入口点，在url解析时调用

        """

     for key in initkwargs:

     #cls.http_method_names：

     #[u'get', u'post', u'put', u'patch', u'delete', u'head', u'options', u'trace']

            if key in cls.http_method_names:

                raise TypeError("You tried to pass in the %s method name as a "

                                "keyword argument to %s(). Don't do that."

                                % (key, cls.__name__))

            if not hasattr(cls, key):

                raise TypeError("%s() received an invalid keyword %r. as_view "

                                "only accepts arguments that are already "

                                "attributes of the class." % (cls.__name__, key))

        #print(cls)  #<class 'app1.views.CBV'>

        def view(request, *args, **kwargs):

            self = cls(**initkwargs)  #实例化CBV对象

            if hasattr(self, 'get') and not hasattr(self, 'head'):

                self.head = self.get

            self.request = request

            #print(request)    <WSGIRequest: GET '/cbv'>

            #print(request.method)  GET

            self.args = args

            self.kwargs = kwargs

            return self.dispatch(request, *args, **kwargs)#调用dispatch方法，将<WSGIRequest: GET '/cbv'>传入

        view.view_class = cls

        view.view_initkwargs = initkwargs

        # take name and docstring from class

        update_wrapper(view, cls, updated=())

        # and possible attributes set by decorators

        # like csrf_exempt from dispatch

        update_wrapper(view, cls.dispatch, assigned=())

        return view

    def dispatch(self, request, *args, **kwargs):

        # Try to dispatch to the right method; if a method doesn't exist,

        # defer to the error handler. Also defer to the error handler if the

        # request method isn't on the approved list.

        if request.method.lower() in self.http_method_names:

            handler = getattr(self, request.method.lower(), self.http_method_not_allowed) #去调用对应的函数

        else:

            handler = self.http_method_not_allowed

        return handler(request, *args, **kwargs)

推荐：介绍——基于类的视图（class-based view）

3.业务处理

-----根据个人需求自定义

-----对于框架：基本操作是操作数据库

　　---pymysql   （原生）

　　---SQLAlchemy

　　---Django中orm

-----响应内容：返回给用户的结果：响应头和响应体

我们写的HTTPResponse是写在响应体中

响应头的定制：

    def post(self,request):

        ret =  HttpResponse("<h1>post</h1>")
　　　　 #下面为设置请求头

        ret['h1'] ='v1'

        ret.set_cookie('c1','v1')

        ret.set_cookie('c2','v2')

        '''

        响应头：h1=v1

                cookies:c1=v1;c2=v2

        响应体：<h1>post</h1>

        请求头信息：

        Content-Length:

        Content-Type:text/html; charset=utf-

        Date:Wed,  Mar  :: GMT

        h1:v1

        Server:WSGIServer/0.1 Python/2.7.

        Set-Cookie:c2=v2; Path=/

        Set-Cookie:c1=v1; Path=/

        X-Frame-Options:SAMEORIGIN

        '''

        return ret

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