Django REST framework 版本

API 版本控制允许我们在不同的客户端之间更改行为（同一个接口的不同版本会返回不同的数据）。 DRF提供了许多不同的版本控制方案。

可能会有一些客户端因为某些原因不再维护了，但是我们后端的接口还要不断的更新迭代，这个时候通过版本控制返回不同的内容就是一种不错的解决方案。

DRF提供的版本控制方案

DRF提供了五种版本控制方案，如下图：

版本控制系统的使用

全局配置

这里我们以 URLPathVersioning 为例，还是在项目的settings.py中REST_FRAMEWORK配置项下配置：

REST_FRAMEWORK = {
    ...
    'DEFAULT_VERSIONING_CLASS': 'rest_framework.versioning.URLPathVersioning',
    'DEFAULT_VERSION': 'v1',           # 默认的版本
    'ALLOWED_VERSIONS': ['v1', 'v2'],  # 有效的版本
    'VERSION_PARAM': 'version',        # 版本的参数名与URL conf中一致
}

局部配置

注意，通常我们是不会单独给某个视图设置版本控制的，如果你确实需要给单独的视图设置版本控制，你可以在视图中设置versioning_class属性，如下：

class PublisherViewSet(ModelViewSet):

    ...
    versioning_class = URLPathVersioning

urls.py

urlpatterns = [
    ...
    url(r'^(?P<version>[v1|v2]+)/publishers/$', views.PublisherViewSet.as_view({'get': 'list', 'post': 'create'})),
    url(r'^(?P<version>[v1|v2]+)/publishers/(?P<pk>\d+)/$', views.PublisherViewSet.as_view({'get': 'retrieve', 'put': 'update', 'delete': 'destroy'})),

]

我们在视图中可以通过访问 request.version 来获取当前请求的具体版本，然后根据不同的版本来返回不同的内容：

我们可以在视图中自定义具体的行为，下面以不同的版本返回不同的序列化类为例

class PublisherViewSet(ModelViewSet):

    def get_serializer_class(self):
        """不同的版本使用不同的序列化类"""
        if self.request.version == 'v1':
            return PublisherModelSerializerVersion1
        else:
            return PublisherModelSerializer
    queryset = models.Publisher.objects.all()

REST framework 提供的默认版本的源码

############################## versioning.py #############################
# coding: utf-8
from __future__ import unicode_literals

import re

from django.utils.translation import ugettext_lazy as _

from rest_framework import exceptions
from rest_framework.compat import unicode_http_header
from rest_framework.reverse import _reverse
from rest_framework.settings import api_settings
from rest_framework.templatetags.rest_framework import replace_query_param
from rest_framework.utils.mediatypes import _MediaType


# 基础类，其他类要继承此类
class BaseVersioning(object):
    default_version = api_settings.DEFAULT_VERSION           # 配置文件中获取相应信息
    allowed_versions = api_settings.ALLOWED_VERSIONS
    version_param = api_settings.VERSION_PARAM

    def determine_version(self, request, *args, **kwargs):    # 必须实现的类
        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):                   # 检测版本是否允许
        if not self.allowed_versions:
            return True
        return ((version is not None and version == self.default_version) or
                (version in self.allowed_versions))

# 版本信息在头部
class AcceptHeaderVersioning(BaseVersioning):
    """
    GET /something/ HTTP/1.1
    Host: example.com
    Accept: application/json; version=1.0
    """
    invalid_version_message = _('Invalid version in "Accept" header.')

    def determine_version(self, request, *args, **kwargs):
        media_type = _MediaType(request.accepted_media_type)
        version = media_type.params.get(self.version_param, self.default_version)
        version = unicode_http_header(version)
        if not self.is_allowed_version(version):
            raise exceptions.NotAcceptable(self.invalid_version_message)
        return version

    # We don't need to implement `reverse`, as the versioning is based
    # on the `Accept` header, not on the request URL.


# 版本信息在url中
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 version is None:
            version = 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
        )


class NamespaceVersioning(BaseVersioning):
    """
    To the client this is the same style as `URLPathVersioning`.
    The difference is in the backend - this implementation uses
    Django's URL namespaces to determine the version.

    An example URL conf that is namespaced into two separate versions

    # users/urls.py
    urlpatterns = [
        url(r'^/users/$', users_list, name='users-list'),
        url(r'^/users/(?P<pk>[0-9]+)/$', users_detail, name='users-detail')
    ]

    # urls.py
    urlpatterns = [
        url(r'^v1/', include('users.urls', namespace='v1')),
        url(r'^v2/', include('users.urls', namespace='v2'))
    ]

    GET /1.0/something/ HTTP/1.1
    Host: example.com
    Accept: application/json
    """
    invalid_version_message = _('Invalid version in URL path. Does not match any version namespace.')

    def determine_version(self, request, *args, **kwargs):
        resolver_match = getattr(request, 'resolver_match', None)
        if resolver_match is None or not resolver_match.namespace:
            return self.default_version

        # Allow for possibly nested namespaces.
        possible_versions = resolver_match.namespace.split(':')
        for version in possible_versions:
            if self.is_allowed_version(version):
                return version
        raise exceptions.NotFound(self.invalid_version_message)

    def reverse(self, viewname, args=None, kwargs=None, request=None, format=None, **extra):
        if request.version is not None:
            viewname = self.get_versioned_viewname(viewname, request)
        return super(NamespaceVersioning, self).reverse(
            viewname, args, kwargs, request, format, **extra
        )

    def get_versioned_viewname(self, viewname, request):
        return request.version + ':' + viewname


class HostNameVersioning(BaseVersioning):
    """
    GET /something/ HTTP/1.1
    Host: v1.example.com
    Accept: application/json
    """
    hostname_regex = re.compile(r'^([a-zA-Z0-9]+)\.[a-zA-Z0-9]+\.[a-zA-Z0-9]+$')
    invalid_version_message = _('Invalid version in hostname.')

    def determine_version(self, request, *args, **kwargs):
        hostname, separator, port = request.get_host().partition(':')
        match = self.hostname_regex.match(hostname)
        if not match:
            return self.default_version
        version = match.group(1)
        if not self.is_allowed_version(version):
            raise exceptions.NotFound(self.invalid_version_message)
        return version

    # We don't need to implement `reverse`, as the hostname will already be
    # preserved as part of the REST framework `reverse` implementation.


# 通过url参数区分
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.')

    def determine_version(self, request, *args, **kwargs):
        version = request.query_params.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):
        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