DRF对Django请求响应做了技术升级

Django视图是用来处理请求和响应的，Django默认是按Form和Template来设计的，如果要处理以JSON格式为主的RESTful API，那么就需要对Django请求和响应的处理代码进行优化改造，本文就来介绍DRF在这一部分的技术升级。

Request

DRF把Django的HttpRequest扩展成了Request：

其中最核心的属性是request.data，它和request.POST的区别如下：

request.POST # 只处理表单（Form）数据，只支持POST方法 request.data # 处理任何数据，支持POST、PUT、PATCH方法 Response

DRF的Response继承自Django的django.template.response.SimpleTemplateResponse：

Response可以根据客户端的请求render合适的content type：

return Response(data)

我摘取了rendered_content()函数的代码：

@property def rendered_content(self): renderer = getattr(self, 'accepted_renderer', None) accepted_media_type = getattr(self, 'accepted_media_type', None) context = getattr(self, 'renderer_context', None) assert renderer, ".accepted_renderer not set on Response" assert accepted_media_type, ".accepted_media_type not set on Response" assert context is not None, ".renderer_context not set on Response" context['response'] = self media_type = renderer.media_type charset = renderer.charset content_type = self.content_type if content_type is None and charset is not None: content_type = "{}; charset={}".format(media_type, charset) elif content_type is None: content_type = media_type self['Content-Type'] = content_type ret = renderer.render(self.data, accepted_media_type, context) if isinstance(ret, str): assert charset, ( 'renderer returned unicode, and did not specify ' 'a charset value.' ) return ret.encode(charset) if not ret: del self['Content-Type'] return ret Status codes

如果在代码中直接写数字形式的状态码如400，是不容易阅读的，于是DRF提供了标识符如HTTP_400_BAD_REQUEST来替代。我列一些常见的状态码标识符：

HTTP_200_OK = 200 HTTP_201_CREATED = 201 HTTP_204_NO_CONTENT = 204 HTTP_400_BAD_REQUEST = 400 HTTP_401_UNAUTHORIZED = 401 HTTP_403_FORBIDDEN = 403 HTTP_404_NOT_FOUND = 404 HTTP_405_METHOD_NOT_ALLOWED = 405 HTTP_500_INTERNAL_SERVER_ERROR = 500 HTTP_502_BAD_GATEWAY = 502 HTTP_503_SERVICE_UNAVAILABLE = 503 HTTP_504_GATEWAY_TIMEOUT = 504

全部的状态码标识符可以在rest_framework.status模块中看到。

@api_view和APIView

DRF对API视图做了2个封装：

@api_view用于函数视图。

APIView用于类视图。

它们提供了一些新功能，比如：

检查请求是Request对象

添加上下文到Response对象

返回请求错误如405 Method Not Allowed

当request.data格式有误时，抛出ParseError异常

改造views.py

接着就用上面这几个新实现对我们之前写的snippets/views.py进行改造：

from rest_framework import status from rest_framework.decorators import api_view from rest_framework.response import Response from snippets.models import Snippet from snippets.serializers import SnippetSerializer @api_view(['GET', 'POST']) def snippet_list(request): """ List all code snippets, or create a new snippet. """ if request.method == 'GET': snippets = Snippet.objects.all() serializer = SnippetSerializer(snippets, many=True) return Response(serializer.data) elif request.method == 'POST': serializer = SnippetSerializer(data=request.data) if serializer.is_valid(): serializer.save() return Response(serializer.data, status=status.HTTP_201_CREATED) return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST) @api_view(['GET', 'PUT', 'DELETE']) def snippet_detail(request, pk): """ Retrieve, update or delete a code snippet. """ try: snippet = Snippet.objects.get(pk=pk) except Snippet.DoesNotExist: return Response(status=status.HTTP_404_NOT_FOUND) if request.method == 'GET': serializer = SnippetSerializer(snippet) return Response(serializer.data) elif request.method == 'PUT': serializer = SnippetSerializer(snippet, data=request.data) if serializer.is_valid(): serializer.save() return Response(serializer.data) return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST) elif request.method == 'DELETE': snippet.delete() return Response(status=status.HTTP_204_NO_CONTENT)

改动点有这些，添加了@api_view，如：

@api_view(['GET', 'POST'])

使用了状态码标识符，如：

status.HTTP_404_NOT_FOUND

使用request.data替代了 data = JSONParser().parse(request)，如：

serializer = SnippetSerializer(data=request.data)

使用Response()替代了JsonResponse()，如：

return Response(serializer.data, status=status.HTTP_201_CREATED)

request.data和Response()能根据请求的JSON自动处理content type。

添加后缀格式（可选）