Django Rest Framework --序列化、请求数据校验

序列化

基本代码结构

modles.py

 1 from django.db import models
 2 # Create your models here.
 3 
 4 # Create your models here.
 5 class UserGroup(models.Model):
 6     title=models.CharField(max_length=32)
 7 
 8 class UserInfo(models.Model):
 9     user_type_choices=((1,'普通用户'),
10                        (2,"VIP"),
11                        (3,"SVIP"))
12     user_type=models.IntegerField(choices=user_type_choices)
13     group= models.ForeignKey('UserGroup',on_delete=models.CASCADE,null=True)
14     roles=models.ManyToManyField('Role')
15     username=models.CharField(max_length=32,unique=True)
16     password=models.CharField(max_length=32)
17 
18 class UserToken(models.Model):
19     user=models.OneToOneField(to='UserInfo',on_delete=models.CASCADE)
20     token=models.CharField(max_length=64)
21 
22 class Role(models.Model):
23     title=models.CharField(max_length=32)

models.py

urls.py

from django.conf.urls import url, include
from web.views.s6_serializers import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

views.py

class UserinfoSerializer(ModelSerializer):
    # user_type = serializers.CharField(source='get_user_type_display')
    # role = serializers.SerializerMethodField()
　　 #生成url
    group=serializers.HyperlinkedIdentityField(view_name='gu',lookup_url_kwarg='xxx',lookup_field='group_id')
    class Meta:
        model=models.UserInfo
        fields='__all__'
        # fields=['id','username','user_type','role']
        depth=1
    # def get_role(self, row):
    #     roles=row.roles.all()
    #     dict=[]
    #     for item in roles:
    #         dict.append({'ID':item.id,"title":item.title})
    #     return dict

class TestView(APIView):
    def get(self,request,*args,**kwargs):
        #方法一
        # roles=models.Role.objects.all().values('id','title')
        # roles=list(roles)
        # ret=json.dumps(roles,ensure_ascii=False)
        #方法二
        # roles=models.Role.objects.all()
        # ser=RoleSerializer(instance=roles,many=True)
        # ret = json.dumps(ser.data, ensure_ascii=False)

        uesr=models.UserInfo.objects.all()
　　　　　#生成url时，必须添加context参数
        ser=UserinfoSerializer(instance=uesr,many=True,context={'request': request})
        ret = json.dumps(ser.data, ensure_ascii=False)
        return HttpResponse(ret)

源码分析

1.实例化Serializer对象时，many参数的作用?

我们从实例化入手，大家知道在实例化时，首先执行的是__new__方法，然后返回对应的对象实例，所以我们一步步深入，在BaseSerializer类中找到了__new__方法。

根据判断many参数的值，来确定我们需要返回的对象实例。

2.Serializer对象是如何序列化数据的？

从data方法入手，进入data方法，返回self._data，接着我们从最外层寻找to_repersertation方法。

3.如何反向生成url？

字段类型(HyperlinkedIdentityField)就是字段生成url，在上图中，进行第一次to_represention方法是返回的是一个对象。

在HyperlinkedIdentityField类的to_represention最后调用的是django内置的生成url的方法reverse。

请求数据校验

urls.py

from django.conf.urls import url, include
from web.views.s6_serializers import TestView

urlpatterns = [
    url(r'test/', TestView.as_view(), name='test'),
]

views.py

class PasswordValidator(object):
    def __init__(self, base):
        self.base = base

    def __call__(self, value):
        if value != self.base:
            message = 'This field must be %s.' % self.base
            raise serializers.ValidationError(message)

    def set_context(self, serializer_field):
        """
        This hook is called by the serializer instance,
        prior to the validation call being made.
        """
        # 执行验证之前调用,serializer_fields是当前字段对象
        pass

class UserSerializer(serializers.Serializer):
    ut_title = serializers.CharField(source='ut.title')
    user = serializers.CharField(min_length=6)
    pwd = serializers.CharField(error_messages={'required': '密码不能为空'}, validators=[PasswordValidator('666')])
    
        def validate_user (self,value):
        print(value)
        raise exceptions.ValidationError('拒绝你了！！！！')

class TestView(APIView):
    def post(self, request, *args, **kwargs):
        # 验证，对请求发来的数据进行验证
        ser = UserSerializer(data=request.data)
        if ser.is_valid():
            print(ser.validated_data)
        else:
            print(ser.errors)

        return Response('POST请求，响应内容')