Django REST framework

　　一、什么是REST？

• REST与技术无关，代表的是一种软件架构风格，REST是Representational State Transfer的简称，中文翻译为“表征状态转移”
• REST从资源的角度类审视整个网络，它将分布在网络中某个节点的资源通过URL进行标识，客户端应用通过URL来获取资源的表征，获得这些表征致使这些应用转变状态
• REST与技术无关，代表的是一种软件架构风格，REST是Representational State Transfer的简称，中文翻译为“表征状态转移”
• 所有的数据，不过是通过网络获取的还是操作（增删改查）的数据，都是资源，将一切数据视为资源是REST区别与其他架构风格的最本质属性
• 对于REST这种面向资源的架构风格，有人提出一种全新的结构理念，即：面向资源架构（ROA：Resource Oriented Architecture）

　　设计参考：http://www.ruanyifeng.com/blog/2014/05/restful_api.html

　　二、目前如何实现REST API？

　　按照规则，根据不同的请求方式做出不同的处理，并且返回内容以及相应状态码。

　　三、什么是 Django REST framework?

 　　Django REST framework是一个基于Django开发的app，用于快速搭建REST API。

　　1、安装：

pip3 install djangorestframework

　　2、快速使用:

INSTALLED_APPS = [
    ...
    'rest_framework',
]

from rest_framework import routers
from . import views


router = routers.DefaultRouter()
router.register(r'users', views.UserInfoViewSet)

urlpatterns = [
    url(r'^', include(router.urls)),
]

from rest_framework import viewsets
from . import models
from . import serializers

# ########### 1. 基本处理方式 ###########

class UserInfoViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows users to be viewed or edited.
    """
    queryset = models.UserInfo.objects.all().order_by('-id')
    serializer_class = serializers.UserInfoSerializer

from rest_framework import serializers
from . import models

class UserInfoSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = models.UserInfo
        # fields = ('id', 'username', 'pwd','ug') # fields = '__all__'
        exclude = ('ug',)
        depth = 1  # 0<=depth<=10

　　ps：最终访问路径

[GET]          http://127.0.0.1:8000/api/users/
[POST]         http://127.0.0.1:8000/api/users/
[GET]          http://127.0.0.1:8000/api/users/7/
[PUT]          http://127.0.0.1:8000/api/users/7/
[DELETE]       http://127.0.0.1:8000/api/users/7/

　　3、基于CBV

from django.conf.urls import url,include
from django.contrib import admin
from . import views

urlpatterns = [
    url(r'^users/$', views.UserList.as_view()),
    url(r'^users/(?P<pk>[0-9]+)/$', views.UserDetail.as_view()),
]

from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework.request import Request
from rest_framework.parsers import JSONParser
from . import models
from . import serializers


class UserList(APIView):
    def get(self, request, *args, **kwargs):
        user_list = models.UserInfo.objects.all()
        serializer = serializers.MySerializer(instance=user_list, many=True)
        return Response(serializer.data)

    def post(self, request, *args, **kwargs):
        data = JSONParser().parse(request)
        serializer = serializers.MySerializer(data=data)
        if serializer.is_valid():
            # print(serializer.data)
            # print(serializer.errors)
            # print(serializer.validated_data)
            # 如果有instance，则执行update方法；否则，执行create
            serializer.save()
            return Response(serializer.data, status=201)
        return Response(serializer.errors, status=400)


class UserDetail(APIView):
    def get(self, request, *args, **kwargs):
        obj = models.UserInfo.objects.filter(pk=kwargs.get('pk')).first()
        serializer = serializers.MySerializer(obj)
        return Response(serializer.data)

    def delete(self, request, *args, **kwargs):
        obj = models.UserInfo.objects.filter(pk=kwargs.get('pk')).first()
        obj.delete()
        return Response(status=204)

    def put(self, request, *args, **kwargs):
        data = JSONParser().parse(request)
        obj = models.UserInfo.objects.filter(pk=kwargs.get('pk')).first()
        serializer = serializers.MySerializer(obj, data=data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=400)

from rest_framework import serializers
from rest_framework.exceptions import ValidationError
from . import models


class MySerializer(serializers.Serializer):
    id = serializers.IntegerField(read_only=True)
    username = serializers.CharField(required=False, allow_blank=True, max_length=100)
    pwd = serializers.CharField()

    def validate_username(self, value):
        if value == '中国':
            raise ValidationError('用户名中存在敏感字符')
        return value

    def validate_pwd(self, value):
        print(value)
        return value

    def validate(self, attrs):
        print(attrs)
        return attrs

    def create(self, validated_data):
        """
        当执行save方法时，自动调用。instance未传值
        :param validated_data:
        :return:
        """
        print(validated_data)
        return models.UserInfo.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """
        当执行save方法时，自动调用。instance传值
        :param instance:
        :param validated_data:
        :return:
        """
        instance.username = validated_data.get('username', instance.username)
        instance.save()
        return instance

　　4、基于FBV

from django.conf.urls import url,include
from django.contrib import admin
from . import views

urlpatterns = [
    url(r'^users/$', views.user_list),
    url(r'^users/(?P<pk>[0-9]+)/$', views.user_detail),
]

from django.http import JsonResponse,HttpResponse
from rest_framework.response import Response
from rest_framework.parsers import JSONParser
from rest_framework.decorators import api_view
from .serializers import MySerializer
from . import models

@api_view(['GET',"POST"])
def user_list(request):
    """
    List all code snippets, or create a new snippet.
    """
    if request.method == 'GET':
        user_list = models.UserInfo.objects.all()
        serializer = MySerializer(user_list,many=True)
        return Response(serializer.data)

    elif request.method == 'POST':
        data = JSONParser().parse(request)
        serializer = MySerializer(data=data)
        if serializer.is_valid():
            print(serializer.data)
            print(serializer.errors)
            print(serializer.validated_data)
            # 如果有instance，则执行update方法；否则，执行create
            serializer.save()
            return Response(serializer.data, status=201)
        return Response(serializer.errors, status=400)

@api_view(['GET',"POST","PUT"])
def user_detail(request, pk):
    """
    Retrieve, update or delete a code snippet.
    """

    obj = models.UserInfo.objects.filter(pk=pk).first()
    if not obj:
        return HttpResponse(status=404)

    if request.method == 'GET':
        serializer = MySerializer(obj)
        # return JsonResponse(serializer.data,json_dumps_params={'ensure_ascii':False},content_type='application/json;charset=utf-8')
        return Response(serializer.data)

    elif request.method == 'PUT':
        data = JSONParser().parse(request)
        serializer = MySerializer(obj, data=data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        return Response(serializer.errors, status=400)

    elif request.method == 'DELETE':
        obj.delete()
        return Response(status=204)

from rest_framework import serializers
from rest_framework.exceptions import ValidationError
from . import models


class MySerializer(serializers.Serializer):
    id = serializers.IntegerField(read_only=True)
    username = serializers.CharField(required=False, allow_blank=True, max_length=100)
    pwd = serializers.CharField()

    def validate_username(self, value):
        if value == '中国':
            raise ValidationError('用户名中存在敏感字符')
        return value

    def validate_pwd(self, value):
        print(value)
        return value

    def validate(self, attrs):
        print(attrs)
        return attrs

    def create(self, validated_data):
        """
        当执行save方法时，自动调用。instance未传值
        :param validated_data:
        :return:
        """
        print(validated_data)
        return models.UserInfo.objects.create(**validated_data)

    def update(self, instance, validated_data):
        """
        当执行save方法时，自动调用。instance传值
        :param instance:
        :param validated_data:
        :return:
        """
        instance.username = validated_data.get('username', instance.username)
        instance.save()
        return instance

 　　5、权限控制

REST_FRAMEWORK = {
    'DEFAULT_PERMISSION_CLASSES': [
        'permissi.MyPermission',
    ]
}

class MyPermission(object):
    """
    A base class from which all permission classes should inherit.
    """

    def has_permission(self, request, view):
        """
        Return `True` if permission is granted, `False` otherwise.
        """

        return True

    def has_object_permission(self, request, view, obj):
        return True