FBV基于函数的这种类型我们一直在使用,比如:
'''urls.py'''
urlpatterns = [
path("login/", views.login),
]
'''views.py'''
from django.shortcuts import render,HttpResponse
def login(request):
if request.method == "GET":
return HttpResponse("GET 方法")
if request.method == "POST":
username = request.POST.get("user")
password = request.POST.get("pwd")
if username == "Hammer" and password == "123":
return HttpResponse("POST 方法")
else:
return HttpResponse("POST other方法")
# 访问 http://127.0.0.1:8000/login/ 返回:---》GET 方法
基于类的视图,就是使用了类来处理用户的请求,不同的请求我们可以在类中使用不同方法来处理,这样大大的提高了代码的可读性;
基于类的视图实现主要还是通过父类 View 提供的一个静态方法 as_view() ,as_view 方法是基于类的外部接口, 他返回一个视图函数,调用后请求会传递给 dispatch 方法,dispatch 方法再根据不同请求来处理不同的方法。
定义的类要继承父类 View,所以需要先引入库:
'''urls.py'''
urlpatterns = [
path('func2/',views.Func2.as_view()),
]
'''views.py'''
from django.shortcuts import render,HttpResponse
from django.views import View
class Func2(View):
def get(self,request):
return HttpResponse('get 方法')
def post(self,request):
return HttpResponse('post 方法')
# 访问:http://127.0.0.1:8000/func2/ 返回 --》:GET 方法
1、可以通过查看as_view()
源码也可以发现,返回了view
函数的内存地址,那么运行path('func2/',views.Func2.as_view())
,就相当于运行了path('func2/',views.view
,因为Func2.as_view()
的返回值是view
,这样看起来CBV基于类的本质也是基于函数,在满足func2的情况下触发视图函数,源码展示如下:
@classonlymethod # 绑定给类的
def as_view(cls, **initkwargs):
"""Main entry point for a request-response process."""
for key in initkwargs:
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))
def view(request, *args, **kwargs):
self = cls(**initkwargs) # self = Func2() ,生成自己写的类的对象
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
self.setup(request, *args, **kwargs)
if not hasattr(self, 'request'):
raise AttributeError(
"%s instance has no 'request' attribute. Did you override "
"setup() and forget to call super()?" % cls.__name__
)
return self.dispatch(request, *args, **kwargs)
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
dispatch
方法可以从继承的父类中查找,View
# dispatch源码
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)
# getattr反射可以通过字符串获取对象的属性或方法,self自己写的类产生的对象,如果拿不到请求方法,报错http_method_not_allowed,最后可以看出,handler就是我们自己写的方法,通过不同请求来触发
else:
handler = self.http_method_not_allowed
return handler(request, *args, **kwargs)
# 执行我们写的同名(get)请求方法,并返回该方法的返回值
ps:http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
,八个基本请求方式