How can I sequelize belongsToMany? - node.js

Question

How can I belongsToMany two different columns in the same table with the ID in a different table?
User Model
id: {
primaryKey: true,
type: DataTypes.UUID,
defaultValue: DataTypes.UUIDV4
},
firstName: {
type: DataTypes.STRING(255)
}
Message Model
id: {
primaryKey: true,
type: DataTypes.UUID,
defaultValue: DataTypes.UUIDV4
},
userId1: {
type: DataTypes.UUID
},
userId2: {
type: DataTypes.UUID
}
belongsTo
thisModel.belongsTo(userModel, {
foreignKey: 'userId1',
foreignKey: 'userId2' // How can add this one here
})

Answer 1

Suppose your case is a message has a sender(userId1) and a receiver(userId2). Below code will work for this case:
const User = sequelize.define('user', {
id: {
primaryKey: true,
type: DataTypes.UUID,
defaultValue: DataTypes.UUIDV4
},
firstName: {
type: DataTypes.STRING(255)
}
});
const Message = sequelize.define('message', {
id: {
primaryKey: true,
type: DataTypes.UUID,
defaultValue: DataTypes.UUIDV4
},
text: {
type: DataTypes.STRING
},
userId1: {
type: DataTypes.UUID
},
userId2: {
type: DataTypes.UUID
}
});
// define the association
User.hasMany(Message, {
foreignKey: 'userId1',
as: 'sender'
})
User.hasMany(Message, {
foreignKey: 'userId2',
as: 'receiver'
})
Message.belongsTo(User, {
foreignKey: 'userId1',
as: 'sender'
});
Message.belongsTo(User, {
foreignKey: 'userId2',
as: 'receiver'
});
// Example using the association
sequelize.sync({
force: true
})
.then(async () => {
// create some users
await User.bulkCreate([
{ firstName: 'user1'},
{ firstName: 'user2'}
])
const users = await User.findAll()
const [user1, user2] = users
const message = await Message.create({
text: 'hello'
})
await message.setSender(user1)
await message.setReceiver(user2)
console.log(message)
})