我想在两个模型之间引用一个外键。但我得到了一个错误： throw new Error(this.name + '.hasMany called with something that\'s not a subclass of Sequelize.Model'); ^
错误：调用user\u relation.hasmany时使用的对象不是sequelize.model的子类
挤压.js

const Sequelize = require('sequelize');
const config = require('./default.config')
const sequelize = new Sequelize(config.database, config.user, config.password, {
  host: config.host,
  port: config.port,
  dialect: 'mysql',
  timezone: config.timezone,//东八区
  pool: {
    max: 5,
    min: 0,
    acquire: 30000,
    idle: 10000
  }
});

sequelize
  .sync()
  .then(err => {
    console.log('Connection has been established successfully.');
  })
  .catch(err => {
    console.error('Unable to connect to the database:', err);
  });

module.exports = sequelize;

用户模型
const sequelize=require（'sequelize'）；const model=require（'../../config/squelize'）；

const Admin = Model.define('admin', {
  username : {type : sequelize.STRING, allowNull : false},//用户名
  password : {type : sequelize.STRING, allowNull : false},//密码
  details : {type : sequelize.STRING, allowNull : true},//简介
  head_thumb : {type : sequelize.STRING, allowNull : true},//头像
  gender : {type : sequelize.STRING, allowNull : true},//性别
  nickname : {type : sequelize.STRING, allowNull : true},//昵称
  userid : {type : sequelize.INTEGER, autoIncrement : true, primaryKey : true}//用户userid
}, {
  freezeTableName:true
})

module.exports = Admin;

管理关系.js

var Sequelize = require('sequelize');
const Model = require('../../config/squelize');
const Admin = require('./admin.model')

var user_relation = Model.define('user_relation', {
    id : {type : Sequelize.INTEGER, autoIncrement : true, primaryKey : true},
    userid : {type : Sequelize.STRING, allowNull : false},//用户id
    frendid : {type : Sequelize.STRING, allowNull : false}//朋友id
},{
    timestamps:false,
    freezeTableName:true,
});
user_relation.hasMany(Admin,{as:'admin',foreignKey:'userid'})

module.exports = user_relation;

是否有人已经看到类似的错误？我找了几天没有任何问题，如果有人能帮忙我会很感激的，
谢谢！