1. 什么是REST

• 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）

2. 什么是 ？

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

安装：

pip3 install djangorestframework

a. 快速使用

INSTALLED_APPS = [    ...    'rest_framework',]

from rest_framework import routersfrom . import viewsrouter = routers.DefaultRouter()router.register(r'users', views.UserInfoViewSet)urlpatterns = [    url(r'^', include(router.urls)),]

from rest_framework import viewsetsfrom . import modelsfrom . 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 serializersfrom . import modelsclass 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/

b. 基于CBV

from django.conf.urls import url,includefrom django.contrib import adminfrom . import viewsurlpatterns = [    url(r'^users/$', views.UserList.as_view()),    url(r'^users/(?P
       
        [0-9]+)/$', views.UserDetail.as_view()),]
       

from rest_framework.views import APIViewfrom rest_framework.response import Responsefrom rest_framework.request import Requestfrom rest_framework.parsers import JSONParserfrom . import modelsfrom . import serializersclass 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 serializersfrom rest_framework.exceptions import ValidationErrorfrom . import modelsclass 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

c. 基于FBV

from django.conf.urls import url,includefrom django.contrib import adminfrom . import viewsurlpatterns = [    url(r'^users/$', views.user_list),    url(r'^users/(?P
       
        [0-9]+)/$', views.user_detail),]
       

from django.http import JsonResponse,HttpResponsefrom rest_framework.response import Responsefrom rest_framework.parsers import JSONParserfrom rest_framework.decorators import api_viewfrom .serializers import MySerializerfrom . 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 serializersfrom rest_framework.exceptions import ValidationErrorfrom . import modelsclass 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

 e.Serializers字段的参数

1 read_only=False, 2  write_only=False, 3  required=None,  4 default=empty, 5  initial=empty,  6 source=None, 7  label=None, 8  help_text=None, 9  style=None,10 error_messages=None, 11 validators=None,12  allow_null=False

3 有关rest framework 的几点技巧

 

ModelSerializer

1、ModelSerializer 比Serializer封装好了一层，直接自己生成的create和update，不用覆盖了，其实推荐用这个，毕竟Serializer封装的很低级，既然用django，就要用好点的。

正常的应该是这样的

1 class AccountSerializer(serializers.ModelSerializer):2     class Meta:3         model = Account4         fields = ('id', 'account_name', 'users', 'created')5 class AccountSerializer(serializers.ModelSerializer):6     class Meta:7         model = Account8         fields = '__all__'

官网推荐用第一种，因为第二种，改变model时，可能无意会泄露数据

3、当一个model有外键的时候，默认显示的是外键的id，此时要显示外键的所有值可以用下面，depth，会把外键的所有值显示出来

1 class AccountSerializer(serializers.ModelSerializer):2     class Meta:3         model = Account4         fields = ('id', 'account_name', 'users', 'created')5         depth = 1

 

4、如果一个serializer中，要包含出了model以外的字段，可以

1 class AccountSerializer(serializers.ModelSerializer):2     url=serializers.CharField(source='get_absolute_url',3 read_only=True)4     groups = serializers.PrimaryKeyRelatedField(many=True)5 6     class Meta:7         model = Account

外键关联信息的显示解决办法： 几种不同的RelatedField: StringRelatedField                       PrimaryKeyRelatedField                       HyperlinkedRelatedField                       SlugRelatedField                       HyperlinkIdentityField

不同的RelatedField ,显示的内容不同，详见官网http://www.django-rest-framework.org/api-guide/relations/

5、把一个字段变成只读字段，需要如下操作，自增字段默认是只读的，不显式表示也是可以的

1 class AccountSerializer(serializers.ModelSerializer):2     class Meta:3         model = Account4         fields = ('id', 'account_name', 'users', 'created')5         read_only_fields = ('account_name',)6 user = serializers.PrimaryKeyRelatedField(read_only=True, default=serializers.CurrentUserDefault())

6、把某一个字段变为只读，然后存储，通过额外字段指定。

1 class CreateUserSerializer(serializers.ModelSerializer): 2     class Meta: 3         model = User 4         fields = ('email', 'username', 'password') 5         extra_kwargs = {
    'password': {
    'write_only': True}} 6  7     def create(self, validated_data): 8         user = User( 9             email=validated_data['email'],10             username=validated_data['username']11         )12         user.set_password(validated_data['password'])13         user.save()14         return user

7 嵌套关系的序列化方法

1 class TrackSerializer(serializers.ModelSerializer): 2     class Meta: 3         model = Track 4         fields = ('order', 'title', 'duration') 5  6 class AlbumSerializer(serializers.ModelSerializer): 7     tracks = TrackSerializer(many=True) 8  9     class Meta:10         model = Album11         fields = ('album_name', 'artist', 'tracks')12 13     def create(self, validated_data):14         tracks_data = validated_data.pop('tracks')15         album = Album.objects.create(**validated_data)16         for track_data in tracks_data:17             Track.objects.create(album=album, **track_data)18         return album