Python的DjangoREST框架中的序列化及请求和返回

url http://127.0.0.1:8000/snippets/

[{"id": 1, "title": "", "code": "print \"hello, world\"\n", "linenos": false, "language": "python", "style": "friendly"}]
 url http://127.0.0.1:8000/snippets/1/

{"id": 1, "title": "", "code": "print \"hello, world\"\n", "linenos": false, "language": "python", "style": "friendly"}

Request and Response
1. Request Object ——Request对象

rest framework 引入了一个继承自HttpRequest的Request对象，该对象提供了对请求的更灵活解析。request对象的核心部分是request.data属性，类似于request.post, 但在使用WEB API时，request.data更有效。

（1）request.POST # Only handles form data. Only works for 'POST' method.
（2）request.DATA # Handles arbitrary data. Works any HTTP request with content.
2. Response Object ——Response对象
rest framework引入了一个Response 对象，它继承自TemplateResponse对象。它获得未渲染的内容并通过内容协商content negotiation 来决定正确的content type返回给client。

return Response(data) # Renders to content type as requested by the client.
3. Status Codes
在views当中使用数字化的HTTP状态码，会使你的代码不宜阅读，且不容易发现代码中的错误。rest framework为每个状态码提供了更明确的标识。例如HTTP_400_BAD_REQUEST。相比于使用数字，在整个views中使用这类标识符将更好。
4. 封装API views

在编写API views时，REST Framework提供了两种wrappers：

1). @api_viwe 装饰器 ——函数级别

2). APIView 类——类级别

这两种封装器提供了许多功能，例如，确保在view当中能够接收到Request实例；往Response中增加内容以便内容协商content negotiation 机制能够执行。

封装器也提供一些行为，例如在适当的时候返回405 Methord Not Allowed响应；在访问多类型的输入request.DATA时，处理任何的ParseError异常。
5. 汇总

我们开始用这些新的组件来写一些views。

我们不在需要JESONResponse 类（在前一篇中创建），将它删除。删除后我们开始稍微重构下我们的view

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 snippets, or create a new snippet.
  """
  if request.method == 'GET':
    snippets = Snippet.objects.all()
    serializer = SnippetSerializer(snippets)
    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)
    else:
      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 snippet instance.
  """       
  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)
    else:
      return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

  elif request.method == 'DELETE':
    snippet.delete()
    return Response(status=status.HTTP_204_NO_CONTENT)

def snippet_list(request, format=None):
and

def snippet_detail(request, pk, format=None):

from django.conf.urls import patterns, url
from rest_framework.urlpatterns import format_suffix_patterns

urlpatterns = patterns('snippets.views',
  url(r'^snippets/$', 'snippet_list'),
  url(r'^snippets/(?P[0-9]+)$', 'snippet_detail'),
)

urlpatterns = format_suffix_patterns(urlpatterns)