如何将组字段添加到自定义用户？

Question

我在serializer.py中使用了此代码

    group = Group.objects.get()
    group.user_set.add(self.object)

当Group Field只有一个项目并且在DB中添加没有问题时，它可以正常工作。但是当我在“组列表”字段中添加多个项目时，我收到错误：

get() returned more than one Group -- it returned 2!

我能做什么？

Image:For one item Work Fine

Image:With More than one i am getting This Error

这是我的完整代码：

from rest_framework import serializers
from . import models
from django.contrib.auth import get_user_model
from django.contrib.auth.models import Group
User = get_user_model()

class UserSerializer(serializers.ModelSerializer):
    password = serializers.CharField(write_only=True)
    confirm_password = serializers.CharField(write_only=True)
    def validate(self, data):
        if not data.get('password') or not data.get('confirm_password'):
            raise serializers.ValidationError("Please enter a password and ""confirm it.")
        if data.get('password') != data.get('confirm_password'):
            raise serializers.ValidationError("Those passwords don't match.")
        return data
    def create(self, validated_data):
        user = get_user_model().objects.create(
            username=validated_data['username'],
            first_name=validated_data['first_name'],
            last_name=validated_data['last_name'],
            email=validated_data['email']
    )
        group = Group.objects.get()
        group.user_set.add(self.object)
        user.set_password(validated_data['password'])
        user.save()
        return user
    class Meta:
        model = get_user_model()
        fields = (
            'username',
            'password',
            'confirm_password',
            'first_name',
            'last_name',
            'email',
            'groups',
        )