Django Rest Framework源码剖析(四)-----API版本
| 一、简介 |
在我们给外部提供的API中，可会存在多个版本，不同的版本可能对应的功能不同，所以这时候版本使用就显得尤为重要，django rest framework也为我们提供了多种版本使用方法。
| 二、基本使用 |
版本使用方式：
1.在url中传递版本:如http://www.example.com/api?version=v1
和其他组建一样，我们在utils里面建立version.py,添加版本类
#!/usr/bin/env python3 #_*_ coding:utf-8 _*_ #Author:wd from rest_framework.versioning import BaseVersioning class Myversion(BaseVersioning): def determine_version(self, request, *args, **kwargs): myversion=request.query_params.get('version') return myversion
在订单视图中应用版本,(当然直接可以使用request.get获取)
class OrderView(APIView): '''查看订单''' from utils.permissions import MyPremission from utils.version import Myversion authentication_classes = [Authentication,] #添加认证 permission_classes = [MyPremission,] #添加权限控制 versioning_class = Myversion #添加版本 def get(self,request,*args,**kwargs): print(request.version)#获取版本 #当然使用request._request.get('version')也可以 ret = {'code':1000,'msg':"你的订单已经完成",'data':"买了一个mac"} return JsonResponse(ret,safe=True)
models.py
from django.db import models class UserInfo(models.Model): user_type_choice = ( (1,"普通用户"), (2,"会员"), ) user_type = models.IntegerField(choices=user_type_choice) username = models.CharField(max_length=32,unique=True) password = models.CharField(max_length=64) class UserToken(models.Model): user = models.OneToOneField(to=UserInfo) token = models.CharField(max_length=64)
urls.py
from django.conf.urls import url from django.contrib import admin from app01 import views urlpatterns = [ url(r'^api/v1/auth', views.AuthView.as_view()), url(r'^api/v1/order', views.OrderView.as_view()), ]
views.py
from django.shortcuts import HttpResponse from django.http import JsonResponse from rest_framework.views import APIView from rest_framework.authentication import BaseAuthentication from . import models from rest_framework import exceptions import hashlib import time class Authentication(BaseAuthentication): """ 认证类 """ def authenticate(self, request): token = request._request.GET.get("token") toke_obj = models.UserToken.objects.filter(token=token).first() if not toke_obj: raise exceptions.AuthenticationFailed("用户认证失败") return (toke_obj.user, toke_obj) # 这里返回值一次给request.user,request.auth def authenticate_header(self, val): pass def md5(user): ctime = str(time.time()) m = hashlib.md5(bytes(user,encoding="utf-8")) m.update(bytes(ctime,encoding="utf-8")) return m.hexdigest() class AuthView(APIView): """登陆认证""" def dispatch(self, request, *args, **kwargs): return super(AuthView, self).dispatch(request, *args, **kwargs) def get(self, request, *args, **kwargs): return HttpResponse('get') def post(self, request, *args, **kwargs): ret = {'code': 1000, 'msg': "登录成功"} try: user = request._request.POST.get("username") pwd = request._request.POST.get("password") obj = models.UserInfo.objects.filter(username=user, password=pwd).first() if not obj: ret['code'] = 1001 ret['msg'] = "用户名或密码错误" else: token = md5(user) models.UserToken.objects.update_or_create(user=obj, defaults={"token": token}) ret['token'] = token except Exception as e: ret['code'] = 1002 ret['msg'] = "请求异常" return JsonResponse(ret) class OrderView(APIView): '''查看订单''' from utils.permissions import MyPremission from utils.version import Myversion authentication_classes = [Authentication,] #添加认证 permission_classes = [MyPremission,] #添加权限控制 versioning_class = Myversion def get(self,request,*args,**kwargs): print(request.version) ret = {'code':1000,'msg':"你的订单已经完成",'data':"买了一个mac"} return JsonResponse(ret,safe=True)
使用postman发送请求：http://127.0.0.1:8000/api/v1/order?token=7c191332ba452abefe516ff95ea9994a&version=v1，后台可获取版本。
当然上面获取版本方式还有更为简单的获取版本方法，使用QueryParameterVersioning，其就是封装的以上过程。
class OrderView(APIView): '''查看订单''' from utils.permissions import MyPremission from utils.version import Myversion from rest_framework.versioning import QueryParameterVersioning authentication_classes = [Authentication,] #添加认证 permission_classes = [MyPremission,] #添加权限控制 versioning_class = QueryParameterVersioning #该方法获取参数的key为version def get(self,request,*args,**kwargs): print(request.version) ret = {'code':1000,'msg':"你的订单已经完成",'data':"买了一个mac"} return JsonResponse(ret,safe=True)
当然，DRF也提供了可配置的版本，并且还能控制版本使用
settings.py
REST_FRAMEWORK = {#版本配置 "DEFAULT_VERSION":'v1', #默认的版本 "ALLOWED_VERSIONS":['v1','v2'], #允许的版本,这里只允许V1和v2 "VERSION_PARAM":'version' , #get方式url中参数的名字 如?version=v1 }
使用postman验证，发送带token和版本http://127.0.0.1:8000/api/v1/order?token=7c191332ba452abefe516ff95ea9994a&version=v3
结果：
可见版本配置生效。
2.使用url路径传递版本，如http://www.example.com/api/v1，django rest framework 当然也为我们提供了类：URLPathVersioning
为了区分，这里新建url和view，如下：
urls.py
from django.conf.urls import url from django.contrib import admin from app01 import views urlpatterns = [ url(r'^api/v1/auth', views.AuthView.as_view()), url(r'^api/v1/order', views.OrderView.as_view()), url(r'^api/(?P<version>[v1|v2]+)/user', views.UserView.as_view()), # 新建的url ]
UserView
class UserView(APIView): '''查看用户信息''' from rest_framework.versioning import URLPathVersioning versioning_class =URLPathVersioning def get(self,request,*args,**kwargs): print(request.version) #获取版本 res={"name":"wd","age":22} return JsonResponse(res,safe=True)
使用postman请求：http://127.0.0.1:8000/api/v1/user,同样后台能拿到版本结果。
| 三、源码剖析 |
和认证流程一样，请求进来，同样走APIview的dispatch的方法，请阅读注解部分：
1.APIView类的dispatch源码：
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: 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.接着执行self.inital方法：
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. ####版本控制 version, scheme = self.determine_version(request, *args, **kwargs) request.version, request.versioning_scheme = version, scheme # Ensure that the incoming request is permitted #2.实现认证 self.perform_authentication(request) #3.权限判断 self.check_permissions(request) #4.频率限制 self.check_throttles(request)
3.可以看到版本控制是在认证之前，首先下执行version, scheme = self.determine_version(request, *args, **kwargs)，以下是self.determine_version源码：
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: #先判断版本类是否存在(self.versioning_class 是否为存在)，不存在返回tuple，（none,none） return (None, None) scheme = self.versioning_class() #存在返回版本类对象 return (scheme.determine_version(request, *args, **kwargs), scheme) #版本类存在，最后返回版本类对象的determine_version方法结果（也就是返回的版本号），和类对象，
这也就是每个版本类必须要有的方法，用来获取版本。
4.承接 self.determine_version方法执行完成以后，接着执行request.version, request.versioning_scheme = version, scheme，这个不用多说，无非将版本号赋值给request.version属性，版本类对象赋值给request.versioning_scheme,这也就是我们为什么能通过request.version获取版本号的原因。
5.同认证源码一样，self.determine_version方法中使用的版本类self.versioning_class()，在全局中也有配置
class APIView(View): # The following policies may be set at either globally, or per-view. renderer_classes = api_settings.DEFAULT_RENDERER_CLASSES parser_classes = api_settings.DEFAULT_PARSER_CLASSES authentication_classes = api_settings.DEFAULT_AUTHENTICATION_CLASSES throttle_classes = api_settings.DEFAULT_THROTTLE_CLASSES permission_classes = api_settings.DEFAULT_PERMISSION_CLASSES content_negotiation_class = api_settings.DEFAULT_CONTENT_NEGOTIATION_CLASS metadata_class = api_settings.DEFAULT_METADATA_CLASS versioning_class = api_settings.DEFAULT_VERSIONING_CLASS #版本处理类配置
6.基于以上源码分析完成以后，下面我们来剖析下，我们示例中所使用的两个版本处理类，具体分析请看注解：
QueryParameterVersioning(BaseVersioning)
class QueryParameterVersioning(BaseVersioning): """ GET /something/?version=0.1 HTTP/1.1 Host: example.com Accept: application/json """ invalid_version_message = _('Invalid version in query parameter.') ## 当setting.py配置了允许的版本时候，不匹配版本返回的错误信息，可以自己定义 def determine_version(self, request, *args, **kwargs): ## 获取版本方法 version = request.query_params.get(self.version_param, self.default_version) # 通过request.query_paras方法获取（本质request.MATE.get），
default_version默认是version，是在settings中配置的 if not self.is_allowed_version(version): #不允许的版本抛出异常 raise exceptions.NotFound(self.invalid_version_message) return version #无异常则返回版本号 def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra): #url 反解析，可以通过该方法生成请求的url，后面会有示例 url = super(QueryParameterVersioning, self).reverse( viewname, args, kwargs, request, format, **extra ) if request.version is not None: return replace_query_param(url, self.version_param, request.version) return url
URLPathVersioning
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.') # 不允许的版本信息，可定制 def determine_version(self, request, *args, **kwargs): ## 同样实现determine_version方法获取版本 version = kwargs.get(self.version_param, self.default_version) # 由于传递的版本在url的正则中，所以从kwargs中获取，self.version_param默认是version if not self.is_allowed_version(version): raise exceptions.NotFound(self.invalid_version_message) # 没获取到，抛出异常 return version # 正常获取，返回版本号 def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra): # url反解析，后面会有示例 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
这个版本类都继承了BaseVersioning：
class BaseVersioning(object): default_version = api_settings.DEFAULT_VERSION #默默人版本配置 allowed_versions = api_settings.ALLOWED_VERSIONS #允许版本配置 version_param = api_settings.VERSION_PARAM #版本key配置 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))
| 四、利用版本反向生成URL |
以URLPathVersioning为例，其本质也是用的django的url反向解析方法，实现过程这里就不用过多说明，有兴趣可以自己看源码。
1.配置url，为view取别名
urlpatterns = [ url(r'^api/v1/auth', views.AuthView.as_view()), url(r'^api/v1/order', views.OrderView.as_view()), url(r'^api/(?P<version>[v1|v2]+)/user', views.UserView.as_view(),name="user_view"), ]
2.利用reverse方法反向生成请求的url,UserView视图。
class UserView(APIView): '''查看用户信息''' from rest_framework.versioning import URLPathVersioning versioning_class =URLPathVersioning def get(self,request,*args,**kwargs): print(request.version) url = request.versioning_scheme.reverse(viewname='user_view', request=request) #versioning_scheme已经在源码中分析过了，就是版本类实例化的对象 print(url) res={"name":"wd","age":22} return JsonResponse(res,safe=True)
使用postman发请求：http://127.0.0.1:8000/api/v1/user查看结果如下：
| 五、总结 |
对于版本控制来说，其实没必要自己去定义或自己写版本处理的类，推荐使用全局配置，以及URLPathVersioning类。
具体配置：
# 全局配置 REST_FRAMEWORK = { "DEFAULT_VERSIONING_CLASS":"rest_framework.versioning.URLPathVersioning", #类的路径 "DEFAULT_VERSION":'v1', #默认的版本 "ALLOWED_VERSIONS":['v1','v2'], #允许的版本 # "VERSION_PARAM":'version' #使用QueryParameterVersioning时候进行的配置，get请求时候传递的参数的key } #单一视图 versioning_class =URLPathVersioning
版权声明：本文为wdliu原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。