django class based view 代码分析

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django class based view 代码分析

  1. url.py入手

    class view url配置一般这样写

    url(r'^module_detail/(?P<pk>(\d+))/$' ModuleDetailView.as_view(), name='module_detail'),

    关键方法是as_view()。

  2. as_view() 源码

    as_view()方法实际是个闭包， 返回了一个处理函数， 把class view 变成了function view， 源码如下：

    
@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

    还可以看到， 方法中实际调用了self.dispatch(request, *args, **kwargs)

  3. self.dispatch做了什么？
    直接看dispatch代码

    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)
else:
    handler = self.http_method_not_allowed
return handler(request, *args, **kwargs)

    通过getattr方法动态调用对应的method， 如get, post等

  4. 看一个DetailView的实现方式

    • 类图

    image