062.Python前段框架Django视图CBV

一 CBV与FBV

CBV：Class Based View
FBV：Function Based View
之前写过的都是基于函数的view，就叫FBV。还可以把view写成基于类的，那就是CBV。

1.1 创建项目

root@darren-virtual-machine:~/PycharmProjects# django-admin startproject cbv_test

root@darren-virtual-machine:~/PycharmProjects# cd cbv_test/

root@darren-virtual-machine:~/PycharmProjects/cbv_test# python3 manage.py startapp app01

setting注册app

INSTALLED_APPS = [

    'django.contrib.admin',

    'django.contrib.auth',

    'django.contrib.contenttypes',

    'django.contrib.sessions',

    'django.contrib.messages',

    'django.contrib.staticfiles',

    'app01.apps.App01Config',

]

root@darren-virtual-machine:~/PycharmProjects/cbv_test# mkdir templates

root@darren-virtual-machine:~/PycharmProjects/cbv_test# vim cbv_test/settings.py

TEMPLATES = [

    {

        'BACKEND': 'django.template.backends.django.DjangoTemplates',

        'DIRS': [os.path.join(BASE_DIR,"templates")],

        'APP_DIRS': True,

        'OPTIONS': {

            'context_processors': [

                'django.template.context_processors.debug',

                'django.template.context_processors.request',

                'django.contrib.auth.context_processors.auth',

                'django.contrib.messages.context_processors.messages',

            ],

        },

    },

]

路由分发

from django.contrib import admin

from django.urls import path,include

urlpatterns = [

    path('admin/', admin.site.urls),

    path('app01/',include(app01.urls)),

]

配置一个登录页面

<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<h3>用户登录</h3>

<form action="" method="POST">

    {% csrf_token %}

    <p>用户名：<input type="text" name="username"></p>

    <p>密 码：<input type="password" name="password"></p>

    <input type="submit">

</form>

</body>

</html>

url文件

from django.urls import  path,re_path

from app01 import views

urlpatterns = [

    path('login/',views.login),

]

views视图文件

from django.shortcuts import render,redirect,HttpResponse

# Create your views here.

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

访问

1.2 使用CBV改写

urls文件

from django.urls import  path,re_path

from app01 import views

urlpatterns = [

    path('login_fbv/',views.login),

    path('login_cbv/', views.Login.as_view()),

]

views文件

from django.shortcuts import render,redirect,HttpResponse

from django.views import  View

# Create your views here.

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

#CBV

class Login(View):

    def get(self,request):

        return render(request, "login.html")

    def post(self,request):

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request, "login.html")

访问http://127.0.0.1:8000/app01/login_cbv/登录

FBV本身就是一个函数，所以和给普通的函数加装饰器无差

1.3 使用装饰器装饰CBV

给CBV加装饰器

from django.shortcuts import render,redirect,HttpResponse

from django.views import  View

import  time

# Create your views here.

def timer(func):

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

        start_time = time.time()

        time.sleep(2)

        rep = func(request,*args,**kwargs)

        end_time = time.time()

        print (end_time-start_time)

        return rep

    return inner

#FBV

@timer

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

1.4 使用装饰器装饰FBV

类中的方法与独立函数不完全相同，因此不能直接将函数装饰器应用于类中的方法，我们需要先将其转换为方法装饰器。Django中提供了method_decorator装饰器用于将函数装饰器转换为方法装饰器。

1.4.1 给某个方法加上装饰器

此例给get方法加上）

from django.shortcuts import render,redirect,HttpResponse

from django.views import  View

import  time

from django.utils.decorators import method_decorator

# Create your views here.

def timer(func):

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

        start_time = time.time()

        time.sleep(2)

        rep = func(request,*args,**kwargs)

        end_time = time.time()

        print (end_time-start_time)

        return rep

    return inner

#FBV

@timer

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

#CBV

class Login(View):

    @method_decorator(timer)

    def get(self,request):

        return render(request, "login.html")

    def post(self,request):

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request, "login.html")

访问http://127.0.0.1:8000/app01/login_cbv/,只有get有,post并没有用到装饰器

[10/Apr/2020 11:27:53] "GET /app01/login_cbv HTTP/1.1" 301 0

2.024909496307373

[10/Apr/2020 11:27:55] "GET /app01/login_cbv/ HTTP/1.1" 200 456

[10/Apr/2020 11:28:05] "POST /app01/login_cbv/ HTTP/1.1" 200 16

1.4.2 加在dispatch方法上面

会给类下的所有方法加上此装饰器

from django.shortcuts import render,redirect,HttpResponse

from django.views import  View

import  time

from django.utils.decorators import method_decorator

# Create your views here.

def timer(func):

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

        start_time = time.time()

        time.sleep(2)

        rep = func(request,*args,**kwargs)

        end_time = time.time()

        print (end_time-start_time)

        return rep

    return inner

#FBV

@timer

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

#CBV

class Login(View):

    @method_decorator(timer)

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

        obj = super().dispatch(request,*args,**kwargs)

        return obj     #这里必须返回,否则Httpresponse错误

    #@method_decorator(timer)

    def get(self,request):

        return render(request, "login.html")

    def post(self,request):

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request, "login.html")

访问http://127.0.0.1:8000/app01/login_cbv

[10/Apr/2020 11:35:08] "GET /app01/login_cbv/ HTTP/1.1" 200 456

2.01680588722229

2.00297474861145

[10/Apr/2020 11:35:16] "POST /app01/login_cbv/ HTTP/1.1" 200 16

1.4.3加在类上面

from django.shortcuts import render,redirect,HttpResponse

from django.views import  View

import  time

from django.utils.decorators import method_decorator

# Create your views here.

def timer(func):

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

        start_time = time.time()

        time.sleep(2)

        rep = func(request,*args,**kwargs)

        end_time = time.time()

        print (end_time-start_time)

        return rep

    return inner

#FBV

@timer

def login(request):

    if request.method == "GET":

        return render(request,"login.html")

    else:

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request,"login.html")

#CBV

@method_decorator(timer,name="get")
#如果需要给post方法家装饰器,method_decorator(timer,nmae="post"),必须制定name的值,否则报错

class Login(View):

    #@method_decorator(timer)

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

        obj = super().dispatch(request,*args,**kwargs)

        return obj     #这里必须返回,否则Httpresponse错误

    #@method_decorator(timer)

    def get(self,request):

        return render(request, "login.html")

    def post(self,request):

        username = request.POST.get("username")

        password = request.POST.get("password")

        if username == "joy" and password == "123456":

            return HttpResponse("login success...")

        else:

            return render(request, "login.html")

访问http://127.0.0.1:8000/app01/login_cbv/

2.017592191696167

[10/Apr/2020 11:39:04] "GET /app01/login_cbv/ HTTP/1.1" 200 456

[10/Apr/2020 11:39:10] "POST /app01/login_cbv/ HTTP/1.1" 200 16

在给类加装饰器的时候,也可以使用name=dispatch,也可以,关键是必须有这个类存在