Django视图之FBV与CBV

一. CBV与FBV

  CBV:Class Based View

  FBV:Function Based View

  我们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。

  下面我们就以前面所写的图书管理系统中的添加出版社为例:

  FBV版本:

# 新增出版社
def add_publisher(request):
    if request.method == "POST":
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")
    return render(request, "add_publisher.html")

  CBV版本:

from django.views import View
 
 
class AddPublisher(View):
    def get(self, request):
        return render(request, "add_publisher.html")
 
    def post(self, request):
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")

  注意:使用CBV时,urls.py中也做对应的修改:

path('add_publisher/', views.AddPublisher.as_view()),  # 新增出版社  

二. 给视图加装饰器

  1. 使用装饰器装饰FBV

  FBV本身就是一个函数,所以和给普通的函数加装饰器无差:

def wrapper(func):
    def inner(*args, **kwargs):
        start_time = time.time()
        ret = func(*args, **kwargs)
        end_time = time.time()
        print("used:", end_time - start_time)
        return ret
 
    return inner
 
 
# 新增出版社
@wrapper
def add_publisher(request):
    if request.method == "POST":
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")
    return render(request, "add_publisher.html")
  2. 使用装饰器装饰CBV

  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。

  方式一:给某个方法加上装饰器(此例给get方法加上)

from django.views import View
from django.utils.decorators import method_decorator
 
 
class AddPublisher(View):  # CBV版
    @method_decorator(wrapper)
    def get(self, request):
        return render(request, "add_publisher.html")
 
    def post(self, request):
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")

  方式二:加在dispatch方法上面,会给类下的所有方法加上此装饰器

class AddPublisher(View):  # CBV版
    @method_decorator(wrapper)
    def dispatch(self, request, *args, **kwargs):
        obj = super(AddPublisher, self).dispatch(request, *args, **kwargs)
        return obj
 
    def get(self, request):
        return render(request, "add_publisher.html")
 
    def post(self, request):
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")

  方式三:加在类上面

@method_decorator(wrapper, name="post")
@method_decorator(wrapper, name="get")  # 给哪个方法加,就要指定name
class AddPublisher(View):  # CBV版
    def dispatch(self, request, *args, **kwargs):
        obj = super(AddPublisher, self).dispatch(request, *args, **kwargs)
        return obj
 
    def get(self, request):
        return render(request, "add_publisher.html")
 
    def post(self, request):
        pub_name = request.POST.get("name")
        models.Publisher.objects.create(name=pub_name)
        return redirect("/publisher_list/")

  

 

posted @ 2019-05-30 21:23  Michael--chen  阅读(1224)  评论(0编辑  收藏  举报