Rest Framework第二天-序列化组件（下）、解析器
序列化组件（下）
一、rest-framework序列化之ModelSerializer
class BookSerializers(serializers.ModelSerializer):
class Meta:
model = models.Book
# fields = "__all__"
fields=['nid','title','authors','publish']
# exclude=('nid',) #不能跟fields同时用
# depth = 1 #深度控制，写 几 往里拿几层，层数越多，响应越慢，官方建议0--10之间，个人建议最多3层
publish=serializers.SerializerMethodField()
def get_publish(self,obj):
return obj.publish.name
authors=serializers.SerializerMethodField()
def get_authors(self,obj):
ret=obj.authors.all()
ss=AuthorSerializer(ret,many=True)
return ss.data二、生成hypermedialink（极少数）
class BookSerializers(serializers.ModelSerializer):
class Meta:
model = models.Book
fields = "__all__"
# 生成连接，直接查看出版社详情
publish = serializers.HyperlinkedIdentityField(view_name='ttt', lookup_field='publish_id', lookup_url_kwarg='pkk')
authors=serializers.SerializerMethodField()
def get_authors(self,obj):
ret=obj.authors.all()
ss=AuthorSerializer(ret,many=True)
return ss.data
#--------------
res=BookSerializers(ret,many=True,context={'request': request})
#--------------
class Publish(APIView):
def get(self,request,pkk):
print(pkk)
return HttpResponse('ok')
#----路由---
url(r'^publish/(?P\d+)$', views.Publish.as_view(),name='ttt'), 三、序列化组件之请求数据校验和保存功能
class BookSerializers(serializers.ModelSerializer):
class Meta:
model=Book
fields="__all__"
#————————
class BookView(APIView):
def post(self, request):
# 添加一条数据
print(request.data)
bs=BookSerializers(data=request.data)
if bs.is_valid():
bs.save() # 生成记录
return Response(bs.data)
else:
return Response(bs.errors)class BookSerializer1(serializers.Serializer):
title=serializers.CharField(error_messages={'required': '标题不能为空'})
#这种方式要保存，必须重写create方法
通过源码查看检验字段的钩子函数：
#is_valid---->self.run_validation-(执行Serializer的run_validation)-->self.to_internal_value(data)---（执行Serializer的run_validation：485行）
def validate_title(self, value):
from rest_framework import exceptions
raise exceptions.ValidationError('看你不顺眼')
return value
#全局
def validate(self, attrs):
from rest_framework import exceptions
if attrs.get('title')== attrs.get('title2'):
return attrs
else:
raise exceptions.ValidationError('不想等啊')四、序列化组件源码分析
序列化组件，先调用__new__方法，如果many=True，生成ListSerializer对象，如果为False，生成Serializer对象 序列化对象.data方法--调用父类data方法---调用对象自己的to_representation（自定义的序列化类无此方法，去父类找） Aerializer类里有to_representation方法，for循环执行attribute = field.get_attribute(instance) 再去Field类里去找get_attribute方法，self.source_attrs就是被切分的source，然后执行get_attribute方法，source_attrs 当参数传过去，判断是方法就加括号执行，是属性就把值取出来
解析器
一、解析器的作用
根据请求头 content-type 选择对应的解析器对请求体内容进行处理。
有application/json，x-www-form-urlencoded，form-data等格式
二、全局使用解析器
settings文件：
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()),
]视图函数：
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)
# 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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')三、局部使用解析器
a. 仅处理请求头content-type为application/json的请求体
# urls.py文件
from django.conf.urls import url, include
from web.views.s5_parser import TestView
urlpatterns = [
url(r'test/', TestView.as_view(), name='test'),
]# views.py文件
#!/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)
# 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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')b. 仅处理请求头content-type为application/x-www-form-urlencoded 的请求体
# urls.py文件
from django.conf.urls import url, include
from web.views import TestView
urlpatterns = [
url(r'test/', TestView.as_view(), name='test'),
]# views.py文件
#!/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)
# 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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')c. 仅处理请求头content-type为multipart/form-data的请求体
# urls.py文件
from django.conf.urls import url, include
from web.views import TestView
urlpatterns = [
url(r'test/', TestView.as_view(), name='test'),
]# views.py
#!/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)
# 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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')
Title
d. 仅上传文件
# urls.py文件
from django.conf.urls import url, include
from web.views import TestView
urlpatterns = [
url(r'test/(?P[^/]+)', TestView.as_view(), name='test'),
] # views.py文件
#!/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)
# 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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')
Title
e. 同时多个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
# urls.py
from django.conf.urls import url, include
from web.views import TestView
urlpatterns = [
url(r'test/', TestView.as_view(), name='test'),
]# views.py
#!/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')
def put(self, request, *args, **kwargs):
return Response('PUT请求，响应内容')四、源码分析
在调用request.data时，才进行解析，由此入手
@property
def data(self):
if not _hasattr(self, '_full_data'):
self._load_data_and_files()
return self._full_data
查看self._load_data_and_files()方法---->self._data, self._files = self._parse()def _parse(self):
#用户请求头里content_type的值
media_type = self.content_type#self.parsers 就是用户配置的parser_classes = [FileUploadParser,FormParser ]
#self里就有content_type，传入此函数
parser = self.negotiator.select_parser(self, self.parsers)
查看self.negotiator.select_parser(self, self.parsers)
def select_parser(self, request, parsers):
#同过media_type和request.content_type比较，来返回解析器，然后调用解析器的解析方法
#每个解析器都有media_type = 'multipart/form-data'属性
for parser in parsers:
if media_type_matches(parser.media_type, request.content_type):
return parser
return None
最终调用parser的解析方法来解析parsed = parser.parse(stream, media_type, self.parser_context)
Request实例化，parsers=self.get_parsers()
Request(
request,
parsers=self.get_parsers(),
authenticators=self.get_authenticators(),
negotiator=self.get_content_negotiator(),
parser_context=parser_context
)
get_parsers方法，循环实例化出self.parser_classes中类对象
def get_parsers(self):
return [parser() for parser in self.parser_classes]
self.parser_classes 先从类本身找，找不到去父类找即APIVIew 中的
parser_classes = api_settings.DEFAULT_PARSER_CLASSES
api_settings是一个对象，对象里找DEFAULT_PARSER_CLASSES属性，找不到，会到getattr方法
def __getattr__(self, attr):
if attr not in self.defaults:
raise AttributeError("Invalid API setting: '%s'" % attr)try:
#调用self.user_settings方法，返回一个字典，字典再取attr属性
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
user_settings方法 ，通过反射去setting配置文件里找REST_FRAMEWORK属性，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