rest-framework之源码分析
一、View源码分析
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()) def options(self, request, *args, **kwargs): """ Handles responding to requests for the OPTIONS HTTP verb. """ response = http.HttpResponse() response['Allow'] = ', '.join(self._allowed_methods()) response['Content-Length'] = '0' return response def _allowed_methods(self): return [m.upper() for m in self.http_method_names if hasattr(self, m)]
分析：
假设路由是：url(r'^books/$', views.BookView.as_view())，BookView类继承了View 执行顺序是： 先执行View类的as_view()方法，返回了view， 如果路由匹配成功，执行view()，返回dispatch()方法， 执行dispatch()方法，先判断request.method.lower()是否则在http_method_names列表中， 如果在，通过反射，调用该方法，并把结果返回。
二、APIView源码分析
class APIView(View): # The following policies may be set at either globally, or per-view. renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES parser_classes = api_settings.DEFAULT_PARSER_CLASSES authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS metadata_class = api_settings.DEFAULT_METADATA_CLASS versioning_class = api_settings.DEFAULT_VERSIONING_CLASS # Allow dependency injection of other settings to make testing easier. settings = api_settings schema = DefaultSchema() @classmethod def as_view(cls, **initkwargs): """ Store the original class on the view function. This allows us to discover information about the view when we do URL reverse lookups. Used for breadcrumb generation. """ 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 # Note: session based authentication is explicitly CSRF validated, # all other authentication is CSRF exempt. return csrf_exempt(view) @property def allowed_methods(self): """ Wrap Django's private `_allowed_methods` interface in a public property. """ return self._allowed_methods() @property def default_response_headers(self): headers = { 'Allow': ', '.join(self.allowed_methods), } if len(self.renderer_classes) > 1: headers['Vary'] = 'Accept' return headers def http_method_not_allowed(self, request, *args, **kwargs): """ If `request.method` does not correspond to a handler method, determine what kind of exception to raise. """ raise exceptions.MethodNotAllowed(request.method) def permission_denied(self, request, message=None): """ If request is not permitted, determine what kind of exception to raise. """ if request.authenticators and not request.successful_authenticator: raise exceptions.NotAuthenticated() raise exceptions.PermissionDenied(detail=message) def throttled(self, request, wait): """ If request is throttled, determine what kind of exception to raise. """ raise exceptions.Throttled(wait) def get_authenticate_header(self, request): """ If a request is unauthenticated, determine the WWW-Authenticate header to use for 401 responses, if any. """ authenticators = self.get_authenticators() if authenticators: return authenticators[0].authenticate_header(request) def get_parser_context(self, http_request): """ Returns a dict that is passed through to Parser.parse(), as the `parser_context` keyword argument. """ # Note: Additionally `request` and `encoding` will also be added # to the context by the Request object. return { 'view': self, 'args': getattr(self, 'args', ()), 'kwargs': getattr(self, 'kwargs', {}) } def get_renderer_context(self): """ Returns a dict that is passed through to Renderer.render(), as the `renderer_context` keyword argument. """ # Note: Additionally 'response' will also be added to the context, # by the Response object. return { 'view': self, 'args': getattr(self, 'args', ()), 'kwargs': getattr(self, 'kwargs', {}), 'request': getattr(self, 'request', None) } def get_exception_handler_context(self): """ Returns a dict that is passed through to EXCEPTION_HANDLER, as the `context` argument. """ return { 'view': self, 'args': getattr(self, 'args', ()), 'kwargs': getattr(self, 'kwargs', {}), 'request': getattr(self, 'request', None) } def get_view_name(self): """ Return the view name, as used in OPTIONS responses and in the browsable API. """ func = self.settings.VIEW_NAME_FUNCTION return func(self.__class__, getattr(self, 'suffix', None)) def get_view_description(self, html=False): """ Return some descriptive text for the view, as used in OPTIONS responses and in the browsable API. """ func = self.settings.VIEW_DESCRIPTION_FUNCTION return func(self.__class__, html) # API policy instantiation methods def get_format_suffix(self, **kwargs): """ Determine if the request includes a '.json' style format suffix """ if self.settings.FORMAT_SUFFIX_KWARG: return kwargs.get(self.settings.FORMAT_SUFFIX_KWARG) def get_renderers(self): """ Instantiates and returns the list of renderers that this view can use. """ return [renderer() for renderer in self.renderer_classes] def get_parsers(self): """ Instantiates and returns the list of parsers that this view can use. """ return [parser() for parser in self.parser_classes] def get_authenticators(self): """ Instantiates and returns the list of authenticators that this view can use. """ return [auth() for auth in self.authentication_classes] def get_permissions(self): """ Instantiates and returns the list of permissions that this view requires. """ return [permission() for permission in self.permission_classes] def get_throttles(self): """ Instantiates and returns the list of throttles that this view uses. """ return [throttle() for throttle in self.throttle_classes] def get_content_negotiator(self): """ Instantiate and return the content negotiation class to use. """ if not getattr(self, '_negotiator', None): self._negotiator = self.content_negotiation_class() return self._negotiator def get_exception_handler(self): """ Returns the exception handler that this view uses. """ return self.settings.EXCEPTION_HANDLER # API policy implementation methods def perform_content_negotiation(self, request, force=False): """ Determine which renderer and media type to use render the response. """ renderers = self.get_renderers() conneg = self.get_content_negotiator() try: return conneg.select_renderer(request, renderers, self.format_kwarg) except Exception: if force: return (renderers[0], renderers[0].media_type) raise def perform_authentication(self, request): """ Perform authentication on the incoming request. Note that if you override this and simply 'pass', then authentication will instead be performed lazily, the first time either `request.user` or `request.auth` is accessed. """ request.user def check_permissions(self, request): """ Check if the request should be permitted. Raises an appropriate exception if the request is not permitted. """ for permission in self.get_permissions(): if not permission.has_permission(request, self): self.permission_denied( request, message=getattr(permission, 'message', None) ) def check_object_permissions(self, request, obj): """ Check if the request should be permitted for a given object. Raises an appropriate exception if the request is not permitted. """ for permission in self.get_permissions(): if not permission.has_object_permission(request, self, obj): self.permission_denied( request, message=getattr(permission, 'message', None) ) def check_throttles(self, request): """ Check if request should be throttled. Raises an appropriate exception if the request is throttled. """ for throttle in self.get_throttles(): if not throttle.allow_request(request, self): self.throttled(request, throttle.wait()) def determine_version(self, request, *args, **kwargs): """ If versioning is being used, then determine any API version for the incoming request. Returns a two-tuple of (version, versioning_scheme) """ if self.versioning_class is None: return (None, None) scheme = self.versioning_class() return (scheme.determine_version(request, *args, **kwargs), scheme) # Dispatch methods def initialize_request(self, request, *args, **kwargs): """ Returns the initial request object. """ parser_context = self.get_parser_context(request) return Request( request, parsers=self.get_parsers(), authenticators=self.get_authenticators(), negotiator=self.get_content_negotiator(), parser_context=parser_context ) def initial(self, request, *args, **kwargs): """ Runs anything that needs to occur prior to calling the method handler. """ self.format_kwarg = self.get_format_suffix(**kwargs) # Perform content negotiation and store the accepted info on the request neg = self.perform_content_negotiation(request) request.accepted_renderer, request.accepted_media_type = neg # Determine the API version, if versioning is in use. version, scheme = self.determine_version(request, *args, **kwargs) request.version, request.versioning_scheme = version, scheme # Ensure that the incoming request is permitted self.perform_authentication(request) self.check_permissions(request) self.check_throttles(request) def finalize_response(self, request, response, *args, **kwargs): """ Returns the final response object. """ # Make the error obvious if a proper response is not returned assert isinstance(response, HttpResponseBase), ( 'Expected a `Response`, `HttpResponse` or `HttpStreamingResponse` ' 'to be returned from the view, but received a `%s`' % type(response) ) if isinstance(response, Response): if not getattr(request, 'accepted_renderer', None): neg = self.perform_content_negotiation(request, force=True) request.accepted_renderer, request.accepted_media_type = neg response.accepted_renderer = request.accepted_renderer response.accepted_media_type = request.accepted_media_type response.renderer_context = self.get_renderer_context() # Add new vary headers to the response instead of overwriting. vary_headers = self.headers.pop('Vary', None) if vary_headers is not None: patch_vary_headers(response, cc_delim_re.split(vary_headers)) for key, value in self.headers.items(): response[key] = value return response def handle_exception(self, exc): """ Handle any exception that occurs, by returning an appropriate response, or re-raising the error. """ if isinstance(exc, (exceptions.NotAuthenticated, exceptions.AuthenticationFailed)): # WWW-Authenticate header for 401 responses, else coerce to 403 auth_header = self.get_authenticate_header(self.request) if auth_header: exc.auth_header = auth_header else: exc.status_code = status.HTTP_403_FORBIDDEN exception_handler = self.get_exception_handler() context = self.get_exception_handler_context() response = exception_handler(exc, context) if response is None: self.raise_uncaught_exception(exc) response.exception = True return response def raise_uncaught_exception(self, exc): if settings.DEBUG: request = self.request renderer_format = getattr(request.accepted_renderer, 'format') use_plaintext_traceback = renderer_format not in ('html', 'api', 'admin') request.force_plaintext_errors(use_plaintext_traceback) raise # Note: Views are made CSRF exempt from within `as_view` as to prevent # accidental removal of this exemption in cases where `dispatch` needs to # be overridden. def dispatch(self, request, *args, **kwargs): """ `.dispatch()` is pretty much the same as Django's regular dispatch, but with extra hooks for startup, finalize, and exception handling. """ 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 def options(self, request, *args, **kwargs): """ Handler method for HTTP 'OPTIONS' request. """ if self.metadata_class is None: return self.http_method_not_allowed(request, *args, **kwargs) data = self.metadata_class().determine_metadata(request, self) return Response(data, status=status.HTTP_200_OK)
分析：
假设路由是：url(r'^books/$', views.BookView.as_view())，BookView类继承了APIView 先执行BookView的as_view()方法，BookView没有as_view()方法，所以执行父类APIView的as_view()方法 view = super(APIView, cls).as_view(**initkwargs)，执行了View类的as_view()方法，并把结果赋值给view return csrf_exempt(view)，对view进行了csrf去保护处理，并把结果返回给url 如果路由匹配成功，执行View类的view方法，然后执行self.dispatch()方法， 先从BookView类找dispatch()方法，没有，接着从APIView找dispatch()方法，有，所以执行APIView的dispatch()方法， dispatch()方法，对request进行了重新封装，并把原生的request赋给request._request， 然后判断request.method.lower()是否则在http_method_names列表中， 如果在，通过反射，调用该方法，并把结果返回。
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