Django REST framework(请求和响应)

一丶请求对象Request objects

request.POST  # Only handles form data.  Only works for 'POST' method.
request.data  # Handles arbitrary data.  Works for 'POST', 'PUT' and 'PATCH' methods.

请求对象拓展了常规的HttpRequest,核心函数是request.data属性,和request.POST类似.

二丶响应对象Response objects

return Response(data)  # Renders to content type as requested by the client.

响应对象是TemplateResponse类型,这是一种为渲染内容,并且使用内容协商来返回给客户端正确的内容类型.

三丶状态码Status codes

在你的视图（views）中使用纯数字的HTTP 状态码并不总是那么容易被理解。而且如果错误代码出错，很容易被忽略。REST框架为status模块中的每个状态代码（如HTTP_400_BAD_REQUEST）提供更明确的标识符。使用它们来代替纯数字的HTTP状态码是个很好的主意

四丶包装（wrapping）API视图

REST框架提供了两个可用于编写API视图的包装器（wrappers）。

1. 用于基于函数视图的@api_view装饰器。
2. 用于基于类视图的APIView类。

这些包装器提供了一些功能，例如确保你在视图中接收到Request实例，并将上下文添加到Response，以便可以执行内容协商。

包装器还提供了诸如在适当时候返回405 Method Not Allowed响应，并处理在使用格式错误的输入来访问request.data时发生的任何ParseError异常。

五丶一步到位

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)

单个片段视图

@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)

六丶给我们的网址添加可选的格式后缀

views.py下
def snippet_list(request, format=None):

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

urls.py下

from django.conf.urls import url
from rest_framework.urlpatterns import format_suffix_patterns
from snippets import views

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

urlpatterns = format_suffix_patterns(urlpatterns)

七丶查看结果

我们可以像以前一样获取所有snippet的列表。

http http://127.0.0.1:8000/snippets/

HTTP/1.1 200 OK
...
[
  {
    "id": 1,
    "title": "",
    "code": "foo = "bar"
",
    "linenos": false,
    "language": "python",
    "style": "friendly"
  },
  {
    "id": 2,
    "title": "",
    "code": "print "hello, world"
",
    "linenos": false,
    "language": "python",
    "style": "friendly"
  }
]
我们可以通过使用Accept标头来控制我们回复的响应格式：

http http://127.0.0.1:8000/snippets/ Accept:application/json  # 请求JSON
http http://127.0.0.1:8000/snippets/ Accept:text/html         # 请求HTML
或者通过附加格式后缀：

http http://127.0.0.1:8000/snippets.json  # JSON后缀
http http://127.0.0.1:8000/snippets.api   # 浏览器可浏览API后缀
类似地，我们可以使用Content-Type头控制我们发送的请求的格式。

# POST表单数据
http --form POST http://127.0.0.1:8000/snippets/ code="print 123"

{
  "id": 3,
  "title": "",
  "code": "print 123",
  "linenos": false,
  "language": "python",
  "style": "friendly"
}

# POST JSON数据
http --json POST http://127.0.0.1:8000/snippets/ code="print 456"

{
    "id": 4,
    "title": "",
    "code": "print 456",
    "linenos": false,
    "language": "python",
    "style": "friendly"
}
如果你向上述http请求添加了--debug，则可以在请求标头中查看请求类型。

现在可以在浏览器中访问http://127.0.0.1:8000/snippets/查看API。