Django基础之给视图加装饰器

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：
```Python
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

@wrapper

def add_class(request):

if request.method == "POST":

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

models.Classes.objects.create(name=class_name)

return redirect("/classa/")

return render(request, "add_class.html")

<h2>2. 使用装饰器装饰CBV</h2>
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。<br>
django中提供了method_decorator装饰器用于将函数装饰器转化为方法装饰器。<br>
使用method_decorator有2种方法能装饰CBV。

<h3>2.1 给dispatch方法加装饰器</h3>
```Python
from django.vies import View
from django.utils.decorators import method_decorator
from django.shortcuts import render, HttpResponse, redirect

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

class Login(View):
    @method_decorator(wrapper)
    def dispatch(self, request, *args, **kwargs):
        obj = super(Login, self).dispatch(request, *args, **kwargs)
        return obj

    def get(self, request):
        return render(request, "login.html")

    def post(self, request):
        print(request.POST.get("user"))
        return HttpResponse("Login.post")

2.3 在类上添加装饰器（推荐）

```Python
from django.views import View
from django.utils.decorators import method_decorator
from django.shortcuts import render, HttpResponse, redirect

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

@method_decorator(wrapper, name="dispatch")

class AddClass(View):

def get(self, request):
    return render(request, "add_class.html")

def post(self, request):
    class_name = request.POST.get("class_name")
    models.Classes.objects.create(name=class_name)
    return redirect("/class/")