rest framework 之解析器

一、示例

1、api/urls.py

from django.urls import path, re_path
from api.views import UserView, ParserView

urlpatterns = [
    # path('users/', UserView.as_view()),
    re_path('(?P<version>[v1|v2]+)/users/', UserView.as_view(), name='api_user'),

    path('parser/', ParserView.as_view(), name='api_parer'),		# 添加这句
]

2、api/views.py

• JSONParser：只能解析content-type:application/json的头
• FormParser：只能解析content-type:application/x-www-form-urlencoded的头

from rest_framework.parsers import JSONParser, FormParser

class ParserView(APIView):
    parser_classes = [JSONParser, FormParser]

    def post(self, request, *args, **kwargs):
        print(request.data)

        return HttpResponse('解析')

3、使用 postman 发送 json 数据测试后台是否能解析：

（1）、设置为 post 方式，headers 中添加数据类型为 json

（2）、body 中选择 raw，然后选择 json 类型，最后就是在空白处构建要发送的 json 数据（记得是双引号）：

后台结果：

如果是 content-type:application/x-www-form-urlencoded 类型数据，不需要设置请求头，默认就是。但是 body 中需要设置为 x-www-form-urlencoded 。

二、源码分析

1、dispatch()

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
    # 对原生的 request 对象进行加工，丰富了
    # request= Request(request,parsers=self.get_parsers(),authenticators=self.get_authenticators(),negotiator=self.get_content_negotiator(),parser_context=parser_context)
    # 第一个参数为原生的 request 对象，封装原生 request
    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

2、initialize_request()

def initialize_request(self, request, *args, **kwargs):
    """
    Returns the initial request object. 封装原生 request 对象
    """
    parser_context = self.get_parser_context(request)

    return Request(
        request,
        # 获取所有解析器
        parsers=self.get_parsers(),
        authenticators=self.get_authenticators(),
        negotiator=self.get_content_negotiator(),
        parser_context=parser_context
    )

3、get_parsers()

def get_parsers(self):
    """
    Instantiates and returns the list of parsers that this view can use.
    返回次视图可以使用的解析器列表
    """
    return [parser() for parser in self.parser_classes]

4、parser_classes

class APIView(View):

    # The following policies may be set at either globally, or per-view.
    renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES
    # 从 settings 中获取解析器
    parser_classes = api_settings.DEFAULT_PARSER_CLASSES

    # Allow dependency injection of other settings to make testing easier.
    settings = api_settings

5、全局配置解析器 settings：

REST_FRAMEWORK = {
    # 解析器
    "DEFAULT_PARSER_CLASSES":["rest_framework.parsers.JSONParser","rest_framework.parsers.FormParser"]
}

源码流程图

---

根据请求头 content-type 选择对应的解析器就请求体内容进行处理。

三、仅处理请求头 content-type 为 application/json 的请求体

1、urls.py

from django.urls import path, re_path, include
from api.views import TestView2

urlpatterns = [
    re_path(r'(?P<version>[v1|v2]+)/test2', TestView2.as_view()),
]

2、views.py

rom rest_framework.views import APIView
from rest_framework.parsers import JSONParser, FormParser
from rest_framework.response import Response

class TestView2(APIView):
    parser_classes = [JSONParser]

    def post(self, request, *args, **kwargs):
        print(request.content_type)    # application/json

        # 获取请求值，并发 JSONParser  处理
        print(request.data)     # {'name': 'rose', 'age': 18}

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)         # <QueryDict: {}>
        print(request.FILES)        # <MultiValueDict: {}>

        return Response('响应内容')

四、仅处理请求头 content-type 为 application/x-www-form-urlencoded 的请求体

1、urls.py

from django.urls import path, re_path, include
from api.views import TestView2

urlpatterns = [
    re_path(r'(?P<version>[v1|v2]+)/test2', TestView2.as_view()),
]

2、views.py

rom rest_framework.views import APIView
from rest_framework.parsers import JSONParser, FormParser
from rest_framework.response import Response

class TestView2(APIView):
    parser_classes = [FormParser]

    def post(self, request, *args, **kwargs):
        print(request.content_type)    # application/x-www-form-urlencoded

        # 获取请求值，并发 JSONParser  处理
        print(request.data)     # <QueryDict: {'123': ['']}>

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)         # <QueryDict: {'123': ['']}>
        print(request.FILES)        # <MultiValueDict: {}>

        return Response('响应内容')

五、仅处理请求头content-type为multipart/form-data的请求体

1、urls.py

from django.urls import path, re_path, include
from api.views import TestView2

urlpatterns = [
    re_path(r'(?P<version>[v1|v2]+)/test2', TestView2.as_view()),
]

2、views.py

rom rest_framework.views import APIView
from rest_framework.parsers import JSONParser, FormParser, MultiPartParser
from rest_framework.response import Response

class TestView2(APIView):
    parser_classes = [MultiPartParser]

    def post(self, request, *args, **kwargs):
        print(request.content_type)    # multipart/form-data

        # 获取请求值，并发 JSONParser  处理
        print(request.data)    

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)        

        return Response('响应内容')

3、upload.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="http://127.0.0.1:8000/test/" method="post" enctype="multipart/form-data">
    <input type="text" name="user" />
    <input type="file" name="img">

    <input type="submit" value="提交">

</form>
</body>
</html>

六、仅上传文件

1、urls.py

from django.urls import path, re_path, include
from api.views import TestView2

urlpatterns = [
    re_path(r'(?P<version>[v1|v2]+)/test2', TestView2.as_view()),
]

2、views.py

rom rest_framework.views import APIView
from rest_framework.parsers import JSONParser, FormParser, MultiPartParser, FileUploadParser
from rest_framework.response import Response

class TestView2(APIView):
    parser_classes = [FileUploadParser]

    def post(self, request, *args, **kwargs):
        print(request.content_type)    

        # 获取请求值，并发 JSONParser  处理
        print(request.data)    

        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)        

        return Response('响应内容')

3、upload.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="http://127.0.0.1:8000/test/" method="post" enctype="multipart/form-data">
    <input type="text" name="user" />
    <input type="file" name="img">

    <input type="submit" value="提交">

</form>
</body>
</html>

七、其他

多个 parser

当同时使用多个 parser 时，rest framework 会根据请求头 content-type 自动进行比对，并使用对应 parser

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import JSONParser, FormParser, MultiPartParser

class TestView(APIView):
    parser_classes = [JSONParser, FormParser, MultiPartParser, ]

    def post(self, request, *args, **kwargs):
        print(request.content_type)

        # 获取请求的值，并使用对应的JSONParser进行处理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data时，request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST请求，响应内容')

---

全局使用

settings.py

REST_FRAMEWORK = {
    'DEFAULT_PARSER_CLASSES':[
        'rest_framework.parsers.JSONParser'
        'rest_framework.parsers.FormParser'
        'rest_framework.parsers.MultiPartParser'
    ]

}

Tips: 个别特殊的值可以通过Django的request对象 request._request 来进行获取

总结

• JSONParser，解析数据类型：content-type:application/json
• FormParser，解析数据类型：content-type:application/x-www-form-urlencoded
• 支持全局配置解析器类型