Sequelize: refer a foreign key between 2 models - mysql

Question

I'm trying to refer a foreign key between 2 models. but I'm getting this error:
throw new AssociationError(`${source.name}.belongsToMany(${target.name}) requires through option, pass either a string or a model`);
AssociationError [SequelizeAssociationError]: Order.belongsToMany(User) requires through option, pass either a string or a model
I check some similar questions but it didn't help.
I started working with Sequelize today so please give an example to answer.
db.js
const fs = require("fs");
const path = require("path");
const Sequelize = require("sequelize");
const basename = path.basename(module.filename);
const db = {};
const sequelize = new Sequelize("name", "user", "password", {
host: "localhost",
dialect: "mysql",
logging: false,
});
fs.readdirSync(__dirname).filter(file =>
(file.indexOf(".") !== 0) &&
(file !== basename) &&
(file.slice(-3) === ".js"))
.forEach(file => {
const model = sequelize.import(path.join(__dirname, file));
db[model.name] = model;
});
Object.keys(db).forEach(modelName => {
if (db[modelName].associate) {
db[modelName].associate(db);
}
});
db.sequelize = sequelize;
db.Sequelize = Sequelize;
module.exports = db;
user.js
const Sequelize = require("sequelize");
module.exports = (sequelize, DataTypes) => {
const User = sequelize.define("User",
{
id: {
type: Sequelize.BIGINT,
autoIncrement: true,
allowNull: false,
primaryKey: true,
},
email: Sequelize.STRING(60),
password: Sequelize.STRING(60),
fullName: {
type: Sequelize.STRING(60),
allowNull: true,
},
},
);
User.associate = function (models) {
models.User.belongsToMany(models.Order);
};
return User;
};
order.js
const Sequelize = require("sequelize");
module.exports = (sequelize, DataTypes) => {
const Order = sequelize.define("Order",
{
id: {
type: Sequelize.BIGINT,
autoIncrement: true,
allowNull: false,
primaryKey: true,
},
title: Sequelize.STRING(60),
orderNumber: Sequelize.STRING(60),
status: Sequelize.STRING(60),
amount: Sequelize.STRING(60),
trackingCode: Sequelize.STRING(60),
},
);
Order.associate = function(models) {
models.Order.belongsToMany(models.User);
};
return Order;
};
when I use lowercase for define name like this:
const User = sequelize.define("user",
{
...
}
);
const User = sequelize.define("order",
{
...
}
);
I get this error:
TypeError: Cannot read property 'belongsToMany' of undefined
sequelize: 5.21.6

Answer 1

I answered similar question here. Please take a look at it. Also pay attention to comments and to the link at the end of the discussion.
If you'll have any questions after reading feel free to ask them in comments to this answer.