rest-framework之解析器


一 解析器的作用

根據請求頭 content-type 選擇對應的解析器對請求體內容進行處理。

有application/json,x-www-form-urlencoded,form-data等格式

二 全局使用解析器

setting里

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

}

路由:

urlpatterns = [
    url(r'test/', TestView.as_view()),
]

視圖函數:

from rest_framework.views import APIView
from rest_framework.response import Response

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

        # 獲取請求的值,並使用對應的JSONParser進行處理
        print(request.data)
        # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值
        print(request.POST)
        print(request.FILES)
        return Response('POST請求,響應內容')

    def put(self, request, *args, **kwargs):
        return Response('PUT請求,響應內容')

 

 

三 局部使用解析器

a. 僅處理請求頭content-type為application/json的請求體

from django.conf.urls import url, include from web.views.s5_parser import TestView urlpatterns = [ url(r'test/', TestView.as_view(), name='test'), ]
#!/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 class TestView(APIView): parser_classes = [JSONParser, ] def post(self, request, *args, **kwargs): print(request.content_type) # 獲取請求的值,並使用對應的JSONParser進行處理 print(request.data) # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值 print(request.POST) print(request.FILES) return Response('POST請求,響應內容') def put(self, request, *args, **kwargs): return Response('PUT請求,響應內容')

b. 僅處理請求頭content-type為application/x-www-form-urlencoded 的請求體

from django.conf.urls import url, include from web.views import TestView urlpatterns = [ url(r'test/', TestView.as_view(), name='test'), ]
#!/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 FormParser class TestView(APIView): parser_classes = [FormParser, ] def post(self, request, *args, **kwargs): print(request.content_type) # 獲取請求的值,並使用對應的JSONParser進行處理 print(request.data) # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值 print(request.POST) print(request.FILES) return Response('POST請求,響應內容') def put(self, request, *args, **kwargs): return Response('PUT請求,響應內容')

c. 僅處理請求頭content-type為multipart/form-data的請求體

from django.conf.urls import url, include from web.views import TestView urlpatterns = [ url(r'test/', TestView.as_view(), name='test'), ]
#!/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 MultiPartParser class TestView(APIView): parser_classes = [MultiPartParser, ] def post(self, request, *args, **kwargs): print(request.content_type) # 獲取請求的值,並使用對應的JSONParser進行處理 print(request.data) # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值 print(request.POST) print(request.FILES) return Response('POST請求,響應內容') def put(self, request, *args, **kwargs): return Response('PUT請求,響應內容')
<!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>

d. 僅上傳文件

from django.conf.urls import url, include from web.views import TestView urlpatterns = [ url(r'test/(?P<filename>[^/]+)', TestView.as_view(), name='test'), ]
#!/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 FileUploadParser class TestView(APIView): parser_classes = [FileUploadParser, ] def post(self, request, filename, *args, **kwargs): print(filename) print(request.content_type) # 獲取請求的值,並使用對應的JSONParser進行處理 print(request.data) # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值 print(request.POST) print(request.FILES) return Response('POST請求,響應內容') def put(self, request, *args, **kwargs): return Response('PUT請求,響應內容')
<!DOCTYPE html>
<html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <form action="http://127.0.0.1:8000/test/f1.numbers" 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>

e. 同時多個Parser

當同時使用多個parser時,rest framework會根據請求頭content-type自動進行比對,並使用對應parser

 

from django.conf.urls import url, include from web.views import TestView urlpatterns = [ url(r'test/', TestView.as_view(), name='test'), ]
#!/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) # 獲取請求的值,並使用對應的JSONParser進行處理 print(request.data) # application/x-www-form-urlencoded 或 multipart/form-data時,request.POST中才有值 print(request.POST) print(request.FILES) return Response('POST請求,響應內容') def put(self, request, *args, **kwargs): return Response('PUT請求,響應內容')

 

四 源碼分析

1 在調用request.data時,才進行解析,由此入手
    @property
    def data(self):
        if not _hasattr(self, '_full_data'):
            self._load_data_and_files()
        return self._full_data
        
2 查看self._load_data_and_files()方法---->self._data, self._files = self._parse()

        def _parse(self):
            #用戶請求頭里content_type的值
            media_type = self.content_type

            #self.parsers 就是用戶配置的parser_classes = [FileUploadParser,FormParser ]
            #self里就有content_type,傳入此函數
            parser = self.negotiator.select_parser(self, self.parsers)

3 查看self.negotiator.select_parser(self, self.parsers)
     def select_parser(self, request, parsers):
        #同過media_type和request.content_type比較,來返回解析器,然后調用解析器的解析方法
        #每個解析器都有media_type = 'multipart/form-data'屬性
        for parser in parsers:
            if media_type_matches(parser.media_type, request.content_type):
                return parser
        return None
    
4 最終調用parser的解析方法來解析parsed = parser.parse(stream, media_type, self.parser_context)

 

1 Request實例化,parsers=self.get_parsers()
    Request(
                request,
                parsers=self.get_parsers(),
                authenticators=self.get_authenticators(),
                negotiator=self.get_content_negotiator(),
                parser_context=parser_context
            )
2 get_parsers方法,循環實例化出self.parser_classes中類對象
    def get_parsers(self):
        return [parser() for parser in self.parser_classes]            

3 self.parser_classes 先從類本身找,找不到去父類找即APIVIew 中的
    parser_classes = api_settings.DEFAULT_PARSER_CLASSES
4 api_settings是一個對象,對象里找DEFAULT_PARSER_CLASSES屬性,找不到,會到getattr方法
        def __getattr__(self, attr):
            if attr not in self.defaults:
                raise AttributeError("Invalid API setting: '%s'" % attr)

            try:
                #調用self.user_settings方法,返回一個字典,字典再取attr屬性
                val = self.user_settings[attr]
            except KeyError:
                # Fall back to defaults
                val = self.defaults[attr]

            # Coerce import strings into classes
            if attr in self.import_strings:
                val = perform_import(val, attr)

            # Cache the result
            self._cached_attrs.add(attr)
            setattr(self, attr, val)
            return val
 5 user_settings方法 ,通過反射去setting配置文件里找REST_FRAMEWORK屬性,找不到,返回空字典
    @property
    def user_settings(self):
        if not hasattr(self, '_user_settings'):
            self._user_settings = getattr(settings, 'REST_FRAMEWORK', {})
        return self._user_settings

 


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