Django REST framework中的版本控制

1.REST framework版本控制的流程分析

1.1 determine_version方法的执行流程

首先,请求到达REST framework的CBV,执行CBV中的dispatch方法再次封装完成request后,执行initial方法.

在REST framework中的版本控制就是在initial函数中调用determine_version方法完成的

来看看源码

initial方法的源码:

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.
    version, scheme = self.determine_version(request, *args, **kwargs)
    request.version, request.versioning_scheme = version, scheme

    # Ensure that the incoming request is permitted
    self.perform_authentication(request)
    self.check_permissions(request)
    self.check_throttles(request)

determine_version方法的源码

def determine_version(self, request, *args, **kwargs):

    if self.versioning_class is None:    # 如果versioning_class为空则返回一个None的元组
        return (None, None)	
    scheme = self.versioning_class()
    return (scheme.determine_version(request, *args, **kwargs), scheme)

determine_version方法中的versioning_class方法又是从哪里来的呢

1.2 versioning_class的由来

在UserView视图函数中没有定义versioning_class,那就要到UserView的父类APIView中去找

在APIView类中定义了versioning_class的信息

class APIView(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

在视图函数中打印versioning_class

None

可以看到默认设置的versioning_class的值是None,这说明我们可以在视图函数中为versioning_class设置一个值

在detemine_version函数的源码中,可以看到versioning_class后面加了一个括号,所以versioning_class是一个函数或一个类

如果versioning_class是一个函数,那么执行versioning_class后会有一个返回值
如果versioning_class是一个类,那么versioning_class加括号就实例化一个类

从rest_framework中导入versioning模块

from rest_framework import versioning

然后进入versioning模块,可以看到这个versioning中定义了6个类

这6个类是BaseVersioning,AcceptHeaderVersioning,URLPathVersioning,NamespaceVersioning,HostNameVersioning,QueryParameterVersioning

而且还可以看到BaseVersioning类是其余5个类的父类.

并且这其余的5个类,每个类中都有一个determine_version方法

在项目的视图函数中导入其中任意一个类,打印versioning_class

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from django.views import View
from rest_framework.versioning import QueryParameterVersioning

class UsersView(APIView):
	versioning_class=QueryParameterVersioning

	def get(self,request,*args,**kwargs):
		print(self.versioning_class)		#打印versioning_class

		return HttpResponse("aaaa")

打印结果

<class 'rest_framework.versioning.QueryParameterVersioning'>

所以versioning_class是一个类,并且versioning_class类中有一个determine_version方法

1.3 REST framework版本控制的流程总结

在initial方法中,执行完determine_version后的返回值被赋值给version, scheme这两个变量

def initial(self, request, *args, **kwargs):

    self.format_kwarg = self.get_format_suffix(**kwargs)

    neg = self.perform_content_negotiation(request)
    request.accepted_renderer, request.accepted_media_type = neg

    version, scheme = self.determine_version(request, *args, **kwargs)
    request.version, request.versioning_scheme = version, scheme

    self.perform_authentication(request)
    self.check_permissions(request)
    self.check_throttles(request)

这两个变量又把determine_version方法的返回值赋值给request.version, request.versioning_scheme这两个变量

在视图函数中打印这两个变量

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.versioning import QueryParameterVersioning

class UsersView(APIView):
	versioning_class=QueryParameterVersioning

	def get(self,request,*args,**kwargs):
		print(self.versioning_class)
		print("request.version:",request.version)
		print("request.versioning_scheme:",request.versioning_scheme)

		return HttpResponse("aaaa")

打印结果

<class 'rest_framework.versioning.QueryParameterVersioning'>
request.version: None
request.versioning_scheme: <rest_framework.versioning.QueryParameterVersioning object at 0x00000000057722B0>

2. REST framework获取版本的方法

在上面的流程分析中,versioning模块中定义了6个类

这6个类是BaseVersioning,AcceptHeaderVersioning,URLPathVersioning,NamespaceVersioning,HostNameVersioning,QueryParameterVersioning

BaseVersioning类是其余5个类的父类,REST framework获取版本调用的就是这5个类

2.1 QueryParameterVersioning:基于url的get传参方式

在settings.py文件的INSTALLED_APPS配置项中引入rest-framework

INSTALLED_APPS = [
    ...
    'rest_framework',
]

配置路由表

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^users/$',views.UsersView.as_view()),
]

视图函数配置获取版本方式为QueryParameterVersioning

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.versioning import QueryParameterVersioning

class UsersView(APIView):
    versioning_class=QueryParameterVersioning

    def get(self,request,*args,**kwargs):
        # print("request:",request.__dict__)
        print("request.version:",request.version)       # 打印版本
        # print(request.version.scheme)
        # print(request.versioning_scheme.reverse("test1",request=request))
        # print(request.versioning_scheme.reverse(viewname="test1",request=request))

        return HttpResponse("aaaa")    

在浏览器中输入http://127.0.0.1:8000/users/?version=v1地址,服务端打印结果

request.version: v1

再把浏览器中的url地址更换为http://127.0.0.1:8000/users/?version=v5,刷新浏览器,服务端打印结果

request.version: v5

2.2 URLPathVersioning:基于url的正则方式

配置url路由信息

urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^(?P<version>w+)/users/$',views.UsersView.as_view()),
]

视图函数配置获取版本方式为URLPathVersioning

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.versioning import URLPathVersioning

class UsersView(APIView):
    versioning_class=URLPathVersioning

    def get(self,request,*args,**kwargs):

        print("request.version:",request.version)   # 打印版本

        return HttpResponse("aaaa")

在浏览器中输入http://127.0.0.1:8000/v1/users/地址,服务端打印结果

request.version: v1

再把浏览器中的url地址更换为http://127.0.0.1:8000/v10/users/,刷新浏览器,服务端打印结果

request.version: v10

2.3 AcceptHeaderVersioning:基于accept请求头方式获取版本信息

在settings.py文件中添加如下配置

REST_FRAMEWORK = {
	'VERSION_PARAM': "version",     # 版本的参数,在url中可以体现
	'DEFAULT_VERSION': 'V1',        # 默认的版本
	'ALLOWED_VERSIONS': ['v1', 'v2','v3']  # 允许的版本
}

urls.py设定为

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
	url(r'^admin/', admin.site.urls),
	url(r'^users/$',views.UsersView.as_view()),
]

视图函数定义

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.versioning import AcceptHeaderVersioning

class UsersView(APIView):
	versioning_class=AcceptHeaderVersioning

	def get(self,request,*args,**kwargs):

		print("request.version:",request.version)	# 获取版本信息

		return HttpResponse("aaaa")

用浏览器打开http://127.0.0.1:8000/users/的url地址

request.version: V1

由于在settings.py文件中已经设定了默认的版本是v1,所以在服务端后台获取到的版本是v1

把settings.py中定义的默认版本更改变v2或者v3,再次刷新浏览器,后台打印的版本信息又会跟着改变

request.version: V2

2.4 NamespaceVersioning:基于django路由系统的namespace

urls.py设定为

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
	url(r'^admin/', admin.site.urls),
	url(r'^v1/users/',([url(r'test/',views.UsersView.as_view(),name='test1')],None,'v1')),
	url(r'^v2/users/',([url(r'test/',views.UsersView.as_view(),name='test2')],None,'v2')),
]

视图函数定义

from django.shortcuts import render,HttpResponse
from rest_framework.views import APIView
from rest_framework.versioning import NamespaceVersioning

class UsersView(APIView):
	versioning_class=NamespaceVersioning

	def get(self,request,*args,**kwargs):
		print("request.version:",request.version)	# 获取版本信息

		return HttpResponse("aaaa")

用浏览器打开http://127.0.0.1:8000/v1/users/test/的url地址

request.version: V1

把url的地址更换为http://127.0.0.1:8000/v2/users/test/,刷新浏览器,后台打印信息如下

request.version: V2

2.5 HostNameVersioning由于要更换电脑的主机名称,所以这里不再进行测试

3. versioning_class的全局配置

在视图函数中定义versioning_class,只能作用于单个类,

如果想整个项目都使用同一种方法来进行版本控制,就可以在settings.py文件中定义全局的versioning_class

在settings.py中配置默认的versioning_class为URLPathVersioning

REST_FRAMEWORK={
	'DEFAULT_VERSIONING_CLASS':'rest_framework.versioning.URLPathVersioning',
}

在前面查看到BaseVersioning的源码时,可以看到还有几个参数可以在settings.py文件中定义的

class BaseVersioning(object):
	default_version = api_settings.DEFAULT_VERSION
	allowed_versions = api_settings.ALLOWED_VERSIONS
	version_param = api_settings.VERSION_PARAM

再来看看这几个参数配置项的作用

REST_FRAMEWORK={			# 默认使用URLPathVersioning类来获取版本信息
	'DEFAULT_VERSIONING_CLASS':'rest_framework.versioning.URLPathVersioning',
	'VERSION_PARAM':"version",			# 版本的参数,在url中可以体现
	'DEFAULT_VERSION':'V1',				# 默认的版本
	'ALLOWED_VERSIONS':['v1','v2']		# 允许的版本
}

修改urls.py文件,使url可以匹配任意长度的字符url

from django.conf.urls import url
from django.contrib import admin
from app01 import views

urlpatterns = [
	url(r'^admin/', admin.site.urls),
	url(r'^(?P<version>w+)/users/$',views.UsersView.as_view()),
]

在浏览器中分别输入http://127.0.0.1:8000/v1/users/和http://127.0.0.1:8000/v2/users/

都可以获取到正确的响应信息

再在浏览器中输入http://127.0.0.1:8000/v3/users/时,浏览器中出现了报错

从这里可以知道,在settings.py文件中设定的url中允许的版本只能是v1或v2,在浏览器中输入的版本是v3,所以就会出现错误了