Django rest framework源码分析（4）----版本
版本
新建一个工程Myproject和一个app名为api
（1）api/models.py
from django.db import models
class UserInfo(models.Model):
USER_TYPE = (
(1,'普通用户'),
(2,'VIP'),
(3,'SVIP')
)
user_type = models.IntegerField(choices=USER_TYPE)
username = models.CharField(max_length=32,unique=True)
password = models.CharField(max_length=64)
group = models.ForeignKey('UserGroup',on_delete=models.CASCADE)
roles = models.ManyToManyField('Role')
class UserToken(models.Model):
user = models.OneToOneField('UserInfo',on_delete=models.CASCADE)
token = models.CharField(max_length=64)
class UserGroup(models.Model):
title = models.CharField(max_length=32)
class Role(models.Model):
title = models.CharField(max_length=32)
（2）Myproject/urls.py
from django.contrib import admin
from django.urls import path,include
urlpatterns = [
#path('admin/', admin.site.urls),
path('api/',include('api.urls') ),
]
（3）api/urls.py
# api/urls.py
from django.urls import path
from .views import UserView
urlpatterns = [
path('users/', UserView.as_view()),
]
（4）views.py
# api/views.py
from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.request import Request
from rest_framework.versioning import QueryParameterVersioning
class UserView(APIView):
versioning_class = QueryParameterVersioning
def get(self,request,*args,**kwargs):
#获取版本
print(request.version)
return HttpResponse('用户列表')
（5）settings.py
#版本
REST_FRAMEWORK = {
"DEFAULT_VERSION":'v1', #默认的版本
"ALLOWED_VERSIONS":['v1','v2'], #允许的版本
"VERSION_PARAM":'version' #GET方式url中参数的名字 ?version=xxx
}
1.url中通过GET传参
QueryParameterVersioning用于去GET参数中取version
http://127.0.0.1:8000/api/users/?version=v2
后台可以看到当前的版本
如果url中没有传版本参数，则显示默认的版本（"DEFAULT_VERSION":'v1'）
http://127.0.0.1:8000/api/users/
如果url传的版本超过settings中的允许范围则报错
http://127.0.0.1:8000/api/users/?version=v3
2.在URLPATH中获取
（1）修改api/urls.py
通常情况我门应该用URLPATH的方式，而不是用前面GET()传参方式
url里面通过正则表达式定义哪些版本,
# api/urls.py
from django.urls import path,re_path
from .views import UserView
urlpatterns = [
re_path('(?P<version>[v1|v2]+)/users/', UserView.as_view()),
]
（2）views.py
URLPathVersioning:去url路径里面获取版本
# api/views.py
from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.request import Request
from rest_framework.versioning import URLPathVersioning
class UserView(APIView):
versioning_class = URLPathVersioning
def get(self,request,*args,**kwargs):
#获取版本
print(request.version)
return HttpResponse('用户列表')
这个URLPathVersioning我们可以放到settings里面，全局配置，就不用写到views里面，每个类都要写一遍了
settings.py
# 版本
# REST_FRAMEWORK = {
# "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
# "DEFAULT_VERSION":'v1', #默认的版本
# "ALLOWED_VERSIONS":['v1','v2'], #允许的版本
# "VERSION_PARAM":'version' #get方式url中参数的名字 ?version=xxx
# }
#全局
REST_FRAMEWORK = {
"DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning",
}
修改views.py
# api/views.py
from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.request import Request
class UserView(APIView):
def get(self,request,*args,**kwargs):
#获取版本
print(request.version)
return HttpResponse('用户列表')
浏览器访问地址
http://127.0.0.1:8000/api/v1/users/
然后后台拿到版本信息
3.反向解析访问的url
（1）api/urls.py
添加name = 'api_user'
# api/urls.py
from django.urls import path,re_path
from .views import UserView
urlpatterns = [
re_path('(?P<version>[v1|v2]+)/users/', UserView.as_view(),name = 'api_user'),
]
（2）views.py
# api/views.py
from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.request import Request
class UserView(APIView):
def get(self,request,*args,**kwargs):
#获取版本
print(request.version)
#获取处理版本的对象
print(request.versioning_scheme)
#获取浏览器访问的url，reverse反向解析
#需要两个参数：viewname就是url中的别名，request=request是url中要传入的参数
#(?P<version>[v1|v2]+)/users/，这里本来需要传version的参数，但是version包含在request里面（源码里面可以看到），所有只需要request=request就可以
url_path = request.versioning_scheme.reverse(viewname='api_user',request=request)
print(url_path)
# self.dispatch
return HttpResponse('用户列表')
浏览器访问
http://127.0.0.1:8000/api/v1/users/
后台获取
源码流程
（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
#对原始request进行加工，丰富了一些功能
#Request(
# request,
# parsers=self.get_parsers(),
# authenticators=self.get_authenticators(),
# negotiator=self.get_content_negotiator(),
# parser_context=parser_context
# )
#request(原始request,[BasicAuthentications对象，])
#获取原生request,request._request
#获取认证类的对象，request.authticators
#1.封装request
request = self.initialize_request(request, *args, **kwargs)
self.request = request
self.headers = self.default_response_headers # deprecate?
try:
#2.认证
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）initial
def initial(self, request, *args, **kwargs):
"""
Runs anything that needs to occur prior to calling the method handler.
"""
self.format_kwarg = self.get_format_suffix(**kwargs)
# Perform content negotiation and store the accepted info on the request
neg = self.perform_content_negotiation(request)
request.accepted_renderer, request.accepted_media_type = neg
# Determine the API version, if versioning is in use.
#request.version获取版本信息
#request.versioning_scheme获取处理版本你的对象
version, scheme = self.determine_version(request, *args, **kwargs)
request.version, request.versioning_scheme = version, scheme
# Ensure that the incoming request is permitted
#4.实现认证
self.perform_authentication(request)
#5.权限判断
self.check_permissions(request)
#6.控制访问频率
self.check_throttles(request)
（3）determine_version
def determine_version(self, request, *args, **kwargs):
"""
If versioning is being used, then determine any API version for the
incoming request. Returns a two-tuple of (version, versioning_scheme)
"""
if self.versioning_class is None:
return (None, None)
scheme = self.versioning_class()
return (scheme.determine_version(request, *args, **kwargs), scheme)
（4）versioning_class
URLPathVersioning源码
class URLPathVersioning(BaseVersioning):
"""
To the client this is the same style as `NamespaceVersioning`.
The difference is in the backend - this implementation uses
Django's URL keyword arguments to determine the version.
An example URL conf for two views that accept two different versions.
urlpatterns = [
url(r'^(?P<version>[v1|v2]+)/users/$', users_list, name='users-list'),
url(r'^(?P<version>[v1|v2]+)/users/(?P<pk>[0-9]+)/$', users_detail, name='users-detail')
]
GET /1.0/something/ HTTP/1.1
Host: example.com
Accept: application/json
"""
invalid_version_message = _('Invalid version in URL path.')
def determine_version(self, request, *args, **kwargs):
version = kwargs.get(self.version_param, self.default_version)
if not self.is_allowed_version(version):
raise exceptions.NotFound(self.invalid_version_message)
return version
def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra):
if request.version is not None:
kwargs = {} if (kwargs is None) else kwargs
kwargs[self.version_param] = request.version
return super(URLPathVersioning, self).reverse(
viewname, args, kwargs, request, format, **extra
)
可以看到
（1）url配置
（2）determine_version
里面有个is_allowed_version，点进去可以看到一些基本参数 （继承BaseVersioning基类）
class BaseVersioning(object):
#默认的版本
default_version = api_settings.DEFAULT_VERSION
#允许的版本
allowed_versions = api_settings.ALLOWED_VERSIONS
#默认参数（是version，比如你可以自定义为v）
version_param = api_settings.VERSION_PARAM
def determine_version(self, request, *args, **kwargs):
msg = '{cls}.determine_version() must be implemented.'
raise NotImplementedError(msg.format(
cls=self.__class__.__name__
))
def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra):
return _reverse(viewname, args, kwargs, request, format, **extra)
def is_allowed_version(self, version):
if not self.allowed_versions:
return True
return ((version is not None and version == self.default_version) or
(version in self.allowed_versions))
来源：oschina
链接：https://my.oschina.net/u/4292686/blog/4320172