利用 Django REST framework 编写 RESTful API

$ pip install djangorestframework
$ pip install markdown

# myproject/myapp/models.py


#! /usr/bin/env python
# -*- coding: utf-8
from __future__ import unicode_literals, absolute_import
import cPickle as pickle

from django.db import models
from django.contrib.auth.models import User


class SerializedField(models.TextField):

    """序列化域
    用 pickle 来实现存储 Python 对象
    """
    __metaclass__ = models.SubfieldBase  # 必须指定该 metaclass 才能使用 to_python

    def validate(self, val):
        raise isinstance(val, basestring)

    def to_python(self, val):
        """从数据库中取出字符串，解析为 python 对象"""
        if val and isinstance(val, unicode):
            return pickle.loads(val.encode(‘utf-8‘))

        return val

    def get_prep_value(self, val):
        """将 python object 存入数据库"""
        return pickle.dumps(val)


class MyModel(models.Model):

    created_at = models.DateTimeField(auto_now_add=True)
    # 注意这里建立了一个外键
    owner = models.ForeignKey(User, related_name=‘mymodels‘)
    field = models.CharField(max_length=100)
    options = SerializedField(max_length=1000, default={})

# myproject/myapp/serializers.py

#! /usr/bin/env python
# -*- coding: utf-8
from __future__ import unicode_literals, absolute_import
import json

from django.contrib.auth.models import User
from rest_framework import serializers

from ..models import MyModel
from .fields import MyCustField


class MyCustField(serializers.CharField):
    """为 Model 中的自定义域额外写的自定义 Serializer Field"""

    def to_representation(self, obj):
        """将从 Model 取出的数据 parse 给 Api"""
        return obj

    def to_internal_value(self, data):
        """将客户端传来的 json 数据 parse 给 Model"""
        return json.loads(data.encode(‘utf-8‘))


class UserSerializer(serializers.ModelSerializer):

    class Meta:
        model = User  # 定义关联的 Model
        fields = (‘id‘, ‘username‘, ‘mymodels‘)  # 指定返回的 fields

    # 这句话的作用是为 MyModel 中的外键建立超链接，依赖于 urls 中的 name 参数
    # 不想要这个功能的话完全可以注释掉
    mymodels = serializers.HyperlinkedRelatedField(
        many=True, queryset=MyModel.objects.all(),
        view_name=‘model-detail‘
    )


class MySerializer(serializers.ModelSerializer):

    options = MyCustField(
        max_length=1000, style={‘base_template‘: ‘textarea.html‘},
    )

    class Meta:
        model = MyModel
        fields = (‘id‘, ‘owner‘, ‘field‘, ‘options‘)
        read_only_fields = (‘owner‘,)  # 指定只读的 field

    def create(self, validated_data):
        """响应 POST 请求"""
        # 自动为用户提交的 model 添加 owner
        validated_data[‘owner‘] = self.context[‘request‘].user
        return MyModel.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """响应 PUT 请求"""
        instance.field = validated_data.get(‘field‘, instance.field)
        instance.save()
        return instance

# myproject/myapp/views.py

#! /usr/bin/env python
# -*- coding: utf-8
from __future__ import unicode_literals, absolute_import

from django.contrib.auth.models import User
from rest_framework import permissions, viewsets, renderers
from rest_framework.decorators import (
    permission_classes, detail_route
)
from rest_framework.response import Response

from .serializers import MySerializer, UserSerializer
from .models import MyModel


class UserViewSet(viewsets.ModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    # 指定权限，下面马上讲到
    permission_classes = (permissions.IsAuthenticated,)


class ModelViewSet(viewsets.ModelViewSet):
    queryset = MyModel.objects.all()
    serializer_class = MySerializer
    permission_classes = (permissions.IsAuthenticatedOrReadOnly,)

    @detail_route(renderer_classes=[renderers.StaticHTMLRenderer])
    def plaintext(self, request, *args, **kwargs):
        """自定义 Api 方法"""
        model = self.get_object()
        return Response(repr(model))

@list_route(methods=[‘post‘, ‘delete‘])
def custom_handler(self, request):
    pass


@detail_route(methods=[‘get‘])
def custom_handler(self, request, pk=None):
    pass

REST_FRAMEWORK = {
    ‘DEFAULT_FILTER_BACKENDS‘: (‘rest_framework.filters.DjangoFilterBackend‘,)
}

class UserListView(generics.ListAPIView):
    queryset = User.objects.all()
    serializer = UserSerializer
    filter_backends = (filters.DjangoFilterBackend,)

filter_backends = (filters.SearchFilter,)
search_fields = (‘username‘, ‘email‘)  # 指定搜索的域

filter_backends = (filters.OrderingFilter,)
ordering_fields = (‘username‘, ‘email‘)

class NodenameFilter(filters.BaseFilterBackend):

    """根据 nodename 来删选
      [nodename]: NeiWang
    """

    def filter_queryset(self, request, queryset, view):
        nodename = request.QUERY_PARAMS.get(‘nodename‘)
        if nodename:
            return queryset.filter(nodename=nodename)
        else:
            return queryset

from rest_framework.exceptions import APIException


class FilterError(APIException):
    status_code = 406
    default_detail = ‘Query arguments error!‘

# settings.py

REST_FRAMEWORK = {
    ‘DEFAULT_PERMISSION_CLASSES‘: (
        ‘rest_framework.permissions.AllowAny‘,
    ),
}

class UserViewSet(viewsets.ReadOnlyModelViewSet):
    queryset = User.objects.all()
    serializer_class = UserSerializer
    # 设置权限，是一个元组
    permission_classes = (permissions.IsAuthenticated,)

# myproject/myapp/premissions.py

#! /usr/bin/env python
# -*- coding: utf-8
from __future__ import unicode_literals, absolute_import

from rest_framework import permissions


class IsOwnerOrReadOnly(permissions.BasePermission):

    def has_permission(self, request, view):
        """针对每一次请求的权限检查"""
        if request.method in permissions.SAFE_METHODS:
            return True

    def has_object_permission(self, request, view, obj):
        """针对数据库条目的权限检查，返回 True 表示允许"""
        # 允许访问只读方法
        if request.method in permissions.SAFE_METHODS:
            return True

        # 非安全方法需要检查用户是否是 owner
        return obj.owner == request.user

# myproject/myapp/urls.py

#! /usr/bin/env python
# -*- coding: utf-8
from __future__ import unicode_literals, absolute_import

from django.conf.urls import url, patterns, include
from rest_framework.routers import DefaultRouter

from . import views


# as_view 方法生成 view
# 可以非常方便的指定 `{Http Method: View Method}`
user_detail = views.UserViewSet.as_view({‘get‘: ‘retrieve‘})
user_list = views.UserViewSet.as_view({‘get‘: ‘list‘, ‘post‘: ‘create‘})

# plaintext 是我的自定义方法，也可以非常方便的指定
modal_plain = views.ModelViewSet.as_view({‘get‘: ‘plaintext‘})
model_detail = views.ModelViewSet.as_view({‘get‘: ‘retrieve‘, ‘post‘: ‘create‘})
model_list = views.ModelViewSet.as_view({‘get‘: ‘list‘, ‘post‘: ‘create‘})

# router 的作用就是自动生成 Api Root 页面
router = DefaultRouter()
router.register(r‘models‘, views.ModelViewSet)
router.register(r‘users‘, views.UserViewSet)


# 不要忘了把 views 注册到 urls 中
urlpatterns = patterns(
    ‘‘,
    url(r‘^‘, include(router.urls)),  # Api Root
    url(r‘^api-auth/‘, include(‘rest_framework.urls‘, namespace=‘rest_framework‘)),
    url(r‘^models/(?P<pk>[0-9]+)/$‘, model_detail, name=‘model-detail‘),
    url(r‘^models/(?P<pk>[0-9]+)/plain/$‘, modal_plain, name=‘model-plain‘),
    url(r‘^models/$‘, model_list, name=‘model-list‘),
    url(r‘^users/$‘, user_list, name=‘user-list‘),
    url(r‘^users/(?P<pk>[0-9]+)/$‘, user_detail, name=‘user-detail‘),
)