class View(object):
"""
Intentionally simple parent class for all views. Only implements
dispatch-by-method and simple sanity checking.
"""
http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']
def __init__(self, **kwargs):
"""
Constructor. Called in the URLconf; can contain helpful extra
keyword arguments, and other things.
"""
# Go through keyword arguments, and either save their values to our
# instance, or raise an error.
for key, value in six.iteritems(kwargs):
setattr(self, key, value)
@classonlymethod
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)
if hasattr(self, 'get') and not hasattr(self, 'head'):
self.head = self.get
self.request = request
self.args = args
self.kwargs = kwargs
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
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)
else:
handler = self.http_method_not_allowed
return handler(request, *args, **kwargs)
def http_method_not_allowed(self, request, *args, **kwargs):
logger.warning(
'Method Not Allowed (%s): %s', request.method, request.path,
extra={'status_code': 405, 'request': request}
)
return http.HttpResponseNotAllowed(self._allowed_methods())
View类的部分源码如上所示。那么平时使用 类 类型的视图是如何解析的呢，下面进行简单介绍：
在url中通常有如下代码
------------------------------------------------------------------------------------------------------------------------------------------------------------->
urlpatterns=[
url(r'^$',SomeView.as_view(),name='index'),
url(r'^about/$',AboutView.as_view(),name='about'),
]
------------------------------------------------------------------------------------------------------------------------------------------------------------->
当有人访问我们的网站根目录的时候，url会在url列表中进行匹配，找到第一个匹配项则把对应的request和其他参数传递给对应的视图
那么在上面的urlpatterns中则一定会匹配到第一条，也就是会把request等信息传递给SomeView.as_view()方法。因为SomeView继承自View，而我们没有去实现as_view()方法
，那么也就是View.as_view()会进行处理。
而处理的过程如下，解释标注在下面代码中：
@classonlymethod
def as_view(cls, **initkwargs):
"""
Main entry point for a request-response process.
"""
for key in initkwargs: #首先是判断 在urlpatterns中as_view有没有传入 http方法的参数，比如我传入一个 get='post',
if key in cls.http_method_names: #如果传入了呢，则会抛出异常，
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): #如果传入的参数并不存在于 视图类中，比如我传入 temp='123',而我的视图类中并没有该属性，也会抛出异常
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): #此方法主要用于返回请求的 视图
self = cls(**initkwargs)
if hasattr(self, 'get') and not hasattr(self, 'head'):#如果类视图实现了 get方法，并且没实现head方法，则head方法等同于get方法
self.head = self.get
self.request = request
self.args = args
self.kwargs = kwargs
return self.dispatch(request, *args, **kwargs) #这是查找类视图中对应方法的重要步骤
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 #把最终的视图处理返回用于调用
------------------------------------------------------------------------------------------------------------------------------------------------------------->
dispatch解释标注在下面代码中
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:#判断request中的方法是不是类视图允许的方法
#如果是允许的方法，则会在对应的类视图中的方法传给给handler用于之后的处理
#如果是允许的方法，但是类视图中没有实现该方法，则把http_method_not_allowed方法返回
handler = getattr(self, request.method.lower(), self.http_method_not_allowed)
else:#是不允许的方法，则返回 http_method_not_allowed方法，源码在开头
handler = self.http_method_not_allowed
return handler(request, *args, **kwargs)欢迎大家批评指正