DRF源码解析1--APIView对request的重新封装

DRF

Word count: 458Reading time: 2 min

 2020/02/19   Share

截取APIView

@classmethod
class APIView(View):
	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
		# 继承了django中View类的的as_view()方法,然后重写了dispatch方法
		view = super().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
		# 在传入request是,apiview对request进行了一次包装
		request = self.initialize_request(request, *args, **kwargs)
		# 此时self.request是initialize_request方法返回的Request
		self.request = request
		self.headers = self.default_response_headers  # deprecate?

		try:
		# 相比于View类的dispatch方法,Apiview在这里进行了一次初始化的方法
		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

进入self.initalize_request()

def initialize_request(self, request, *args, **kwargs):
	parser_context = self.get_parser_context(request)
	# 可以看到, request已经被封装成Request返回,而request则被封装成Request的一个属性
	return Request(
	request,
	parsers=self.get_parsers(),
	authenticators=self.get_authenticators(),
	negotiator=self.get_content_negotiator(),
	parser_context=parser_context
	)

截取Ruquest

class Request:
    def __init__(self, request, parsers=None, authenticators=None,
                 negotiator=None, parser_context=None):
        assert isinstance(request, HttpRequest), (
            'The `request` argument must be an instance of '
            '`django.http.HttpRequest`, not `{}.{}`.'
            .format(request.__class__.__module__, request.__class__.__name__)
        )
		# request被封装了私有属性
        self._request = request
    @property
    def content_type(self):
        meta = self._request.META
		# 封装了content_type方法获取传输类型
        return meta.get('CONTENT_TYPE', meta.get('HTTP_CONTENT_TYPE', ''))

    @property
    def query_params(self):
        """
        More semantically correct name for request.GET.
        """
		# django的view中的request.Get属性封装成了query_params属性
        return self._request.GET

    @property
    def data(self):
        if not _hasattr(self, '_full_data'):
            self._load_data_and_files()
		# django的view中的request.Post属性封装成了data属性
        return self._full_data

我们可以看出~CBV在内部做了一个分发,本质和FBV是一样的。

以后做接口开发的时候，就要用CBV，学习了restful规范，现在就很容易理解我们为什么用CBV了。

Author：liangweijiang

原文链接：https://liangweijiang.github.io/2020/02/19/DRF-01/

发表日期：February 19th 2020, 4:58:37 pm

更新日期：February 19th 2020, 6:08:43 pm

Next Post

DRF源码解析2--viewsets.ModelViewSet对视图的封装

CATALOG

1. 截取APIView
2. 进入self.initalize_request()
3. 截取Ruquest

