FBV（function based views）, A function-based view .FBV Simple and easy to understand , But it's hard to reuse . They can't be like CBV That way, you can inherit from the parent class .FBV The guidelines for writing require us to ： The less view code the better ; View code cannot be repeated ; Views should only handle rendering logic . Business logic should be placed in the data model as much as possible , Or in the form object ; Keep the view code simple ; Use them to write custom 403, 404, 500 Wait for the error handler ; Avoid using nested if block .CBV yes View Class ; The main difference here is that the request is based on HTTP Method named class method , for example GET ,POST ,PUT ,HEAD etc. . therefore , ad locum , We do not need to make a condition to judge that the request is a POST Or is it a GET . The code will jump directly to the correct method , stay View Class handles this logic internally .
from django.shortcuts import render, redirect
def login(request):
if request.method == "GET":
"""
Handle GET request
"""
return render(request, 'login.html')
if request.method == "GET":
"""
Handle POST request
"""
user = request.POST.get('username')
pwd = request.POST.get('password')
if username == 'tony' and password == "123456":
request.session['user'] = user
return redirect('/index/')
return render(request, 'login.html')# urls.py in
url(r'^login/$', views.login),
CBV Is a class based view , Is to use the class to handle the user's request , We can use different methods to deal with different requests in our class , This greatly improves the readability of the code .CBV Allows us to use different instance methods to respond to different HTTP Request method , Not like it FBV Use conditional branch code like that . But the defined class should inherit the parent class View, So we're using CBV You need to import and stock in in advance ：from django.views import View
Priority will be given to the execution of the method corresponding to the request dispatch Method ( stay get/post/put… Before the method ),dispatch() Method will call corresponding methods according to different requests to handle . Actually , We all know what we have learned before Django Of url A request is assigned to a callable function , Not a class , How do you implement a class based view ？ Mainly through the parent class View A static method provided by as_view() ,as_view Method is an external interface based on class , He returns a view function , After the call, the request is passed to dispatch Method ,dispatch Method then processes different methods according to different requests .
from django.shortcuts import render,HttpResponse
from django.views import View
class LoginView(View):
def get(self, request):
"""
Handle GET request
"""
return render(request, 'login.html')
def post(self, request):
"""
Handle POST request
"""
user = request.POST.get('username')
pwd = request.POST.get('password')
if username == 'tony' and password == "123456":
request.session['user'] = user
return redirect('/index/')
return render(request, 'login.html')# urls.py in
url(r'^user/$', views.LoginView.as_view()),
CBV The logic of the entire view function is divided into multiple functions under the class , Rely on function calls to implement complete logic ; Improve code reusability , More flexible , Let developers use object-oriented technology , For example, more inheritance 、 Polymorphism etc. ; You can use different functions for different HTTP Method treatment , Not through a lot if Judge , Improve code readability .
When we use CBV When the way , First of all, pay attention to urls.py To be written in the document “ Class name .as_view()” Mode mapping , Second, in the class we define get/post Methods the names of these methods are not defined by us , But in a fixed pattern ,View Class supports the following methods ：
http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
