django的类视图拥有自动查找指定方法的功能, 通过调用是通过as_view()方法实现
from meduo_mall.demo import views
urlpatterns = [
url(r'register/$', views.Demo.as_view())
]
from django.views.generic import View
class Demo(View):
def get(self, request):
return HttpResponse('get page')
def post(self, request):
return HttpResponse('post page')
为什么as_view能自动匹配指定的方法,
@classonlymethod
def as_view(cls, **initkwargs): # 实际上是一个闭包 返回 view函数
"""
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): # 作用：增加属性， 调用dispatch方法
self = cls(**initkwargs) # 创建一个 cls 的实例对象， cls 是调用这个方法的 类（Demo）
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
self.request = request # 为对象增加 request， args， kwargs 三个属性
self.args = args
self.kwargs = kwargs
return self.dispatch(request, *args, **kwargs) # 找到指定的请求方法， 并调用它
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
def dispatch(self, request, *args, **kwargs):
# Try to dispatch to the right method; if a method doesn't exist,
if request.method.lower() in self.http_method_names: # 判断请求的方法类视图是否拥有， http_method_names=['get', 'post']
handler = getattr(self, request.method.lower(), self.http_method_not_allowed) # 如果存在 取出该方法
else:
handler = self.http_method_not_allowed
return handler(request, *args, **kwargs) # 执行该方法
@classonlymethod
def as_view(cls, **initkwargs): # 实际上是一个闭包 返回 view函数
"""
Main entry point for a request-response process.
"""
def view(request, *args, **kwargs): # 作用：增加属性， 调用dispatch方法
self = cls(**initkwargs) # 创建一个 cls 的实例对象， cls 是调用这个方法的 类（Demo）
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
self.request = request # 为对象增加 request， args， kwargs 三个属性
self.args = args
self.kwargs = kwargs
return self.dispatch(request, *args, **kwargs) # 找到指定的请求方法， 并调用它
return view
def dispatch(self, request, *args, **kwargs):
# Try to dispatch to the right method; if a method doesn't exist,
if request.method.lower() in self.http_method_names: # 判断请求的方法类视图是否拥有， http_method_names=['get', 'post']
handler = getattr(self, request.method.lower(), self.http_method_not_allowed) # 如果存在 取出该方法
else:
handler = self.http_method_not_allowed
return handler(request, *args, **kwargs) # 返回该请求方法执行的结果
def as_view(): # 校验 + 返回view方法
# 一些校验
...
def view(): # 执行视图
# 增加 为对象request, args, kwargs 属性
...
return dispatch() # 调用指定的请求方法
return view
def dispatch(): # 真正的查找指定的方法, 并调用该方法
...
return handler()
调用顺序: as_view --> view --> dispatch
可以看出
as_view实际上是一个闭包, 它的作用做一些校验工作, 再返回view方法.而
view方法的作用是给请求对象补充三个参数, 并调用dispatch方法处理dispatch方法查找到指定的请求方法, 并执行
可以得出结论: 实际上真正实现查找的方法是 dispatch方法