如何使用sequelize在node.js中保存数据？

Question

表客户：

const Customer=sequelize.define('Customer', {
    id_customer: {
        type: DataTypes.INTEGER(10).UNSIGNED,
        allowNull: false,
        primaryKey: true,
        autoIncrement: true
    },
     email: {
        type: DataTypes.STRING(128),
        allowNull: false
    }
// Class Method
Customer.associate = function (models) {
    Customer.belongsToMany(models.Group, {
        through :models.CustomerGroup,
        foreignKey: 'id_customer'
    });
};

CustomerGoup表

   const CustomerGroup = sequelize.define('CustomerGroup', {
           id_customer: {
               type: DataTypes.INTEGER(10).UNSIGNED,
               allowNull: false,
               primaryKey: true
           },
           id_group: {
               type: DataTypes.INTEGER(10).UNSIGNED,
               allowNull: false,
               primaryKey: true
           }
       }

小组表：

       module.exports = function(sequelize, DataTypes) {
           const Group = sequelize.define('Group', {
                       id_group: {
                           type: DataTypes.INTEGER(10).UNSIGNED,
                           allowNull: false,
                           primaryKey: true,
                           autoIncrement: true
                       },
                       reduction: {
                           type: DataTypes.DECIMAL,
                           allowNull: false,
                           defaultValue: '0.00'
                       },
                       price_display_method: {
                           type: DataTypes.INTEGER(4),
                           allowNull: false,
                           defaultValue: '0'
                       },
                       show_prices: {
                           type: DataTypes.INTEGER(1).UNSIGNED,
                           allowNull: false,
                           defaultValue: '1'
                       },
                       date_add: {
                           type: DataTypes.DATE,
                           allowNull: false
                       },
                       date_upd: {
                           type: DataTypes.DATE,
                           allowNull: false
                       }
                   }


// Class Method
Group.associate = function (models) {
    Group.belongsToMany(models.Customer, {
        through :models.CustomerGroup,
        foreignKey: 'id_group'
    });
};

现在我正在尝试将客户保存到 Customer 表中。然后我需要创建一个连接客户和组的记录。所以我需要在表 CustomerGroup 中创建一条记录。 我的代码如下：

   let newCustomer = db.Customer.build({
            email:email,

            group: [
                {id_group: 1}
            ]

        },{
            assoication: [{
                model:db.Group,
                as:'group'
            }]
        });

作为我的代码，我保存了客户信息。但得到错误Unhandled rejection Error: Group (group) is not associated to Customer! 有人可以告诉我我的代码有什么问题吗？感谢