rest_framework ---APIView

APIView源调用流程

1.首先从django项目跟url开始

我们已get请求publish页面为例，如下先在跟目录找到

r'^publish/'  ---->执行对应的函数  views.PublishView.as_view()

urls.py:

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r'^admin/', admin.site.urls),

    url(r'^publish/',views.PublishView.as_view())

]

查找顺序：views.py----->PublishView------>APIView

文字说明：先查找views.py下的PublishView，看看自定义类是否有as_view方法，没有就开始向父类APIView查找,在APIView中有as_view方法，其实通过32行

 　　　　代码我们知道APIView执行的还是它父类View中的as_view方法返回了一个内嵌的view函数，这个函数执行的结果我们可以看到得到的是一个

　　　　　　self.dispatch(request, *args, **kwargs)，这个self很关键，通过 self = cls(**initkwargs)，我们知道这个self就是调用这个类方法的一个实例

　　　　谁来调用这个函数self就是谁的实例，所以在我们这个例子中self指代的及时PublishView的实例对线，所以在调用dispatch方法先从自定义的PublishView中找

　　　　，我们这个class中没有dispatch所以开始找它的父类APIView，在APIView中找到了我们需要的dispatch，所以开始执行这个分发，走到这里我们可以看到

　　　　rest_framework在APIView接口中和CBV的区别就是APIVIew自定义了一个dispatch对CBV的view方法中的dispatch进行了一个拦截，有点类似我们组件中的

　　　　通用父类和自定义配置类

# views.py:

from rest_framework.views import APIView

class PublishView(APIView):

    def get(self,request):
        pass


    def post(self,request):
        pass

# rest_framework/views.py

class APIView(View):
    settings = api_settings
    schema = DefaultSchema()

    @classmethod
    def as_view(cls, **initkwargs):
        
        if isinstance(getattr(cls, 'queryset', None), models.query.QuerySet):
            def force_evaluation():
                raise RuntimeError(
                    'Do not evaluate the `.queryset` attribute directly, '
                    'as the result will be cached and reused between requests. '
                    'Use `.all()` or call `.get_queryset()` instead.'
                )
            cls.queryset._fetch_all = force_evaluation

        view = super(APIView, cls).as_view(**initkwargs)
        view.cls = cls
        view.initkwargs = initkwargs

        return csrf_exempt(view)
　　
　　
def dispatch(self, request, *args, **kwargs):
    
    self.args = args
    self.kwargs = kwargs
    request = self.initialize_request(request, *args, **kwargs)
    self.request = request
    self.headers = self.default_response_headers  # deprecate?

    try:
        self.initial(request, *args, **kwargs)

        # Get the appropriate handler method
        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

        response = handler(request, *args, **kwargs)

    except Exception as exc:
        response = self.handle_exception(exc)

    self.response = self.finalize_response(request, response, *args, **kwargs)
    return self.response

class View(object):
   
    http_method_names = ['get', 'post', 'put', 'patch', 'delete', 'head', 'options', 'trace']

    @classonlymethod
    def as_view(cls, **initkwargs):
       
        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