Can't update a specific column in Sequelize - node.js

Question

I have a model. It is for the intermediate(pivot) table.
UserCars.init({
carId: DataTypes.INTEGER,
userId: DataTypes.INTEGER,
title: DataTypes.STRING,
}, {
timestamps: false,
sequelize,
modelName: 'UserCars',
});
and here is my migration for this:
'use strict';
module.exports = {
up: async (queryInterface, Sequelize) => {
await queryInterface.createTable('UserCars', {
carId: {
allowNull: false,
type: Sequelize.INTEGER,
references: {
model: 'Cars',
key: 'id'
},
},
userId: {
allowNull: false,
type: Sequelize.INTEGER,
references: {
model: 'Users',
key: 'id'
},
},
title: {
type: Sequelize.STRING
},
}, {
uniqueKeys: {
Items_unique: {
fields: ['carId', 'userId']
}
}
});
},
down: async (queryInterface, Sequelize) => {
await queryInterface.dropTable('UserCars');
}
};
And I'm doing this below to create/update it:
userCar = await UserCars.findOne({
where: {
carId: 10,
userId: req.user.id,
}
});
if(userCar) {
userCar.userId = 20; // <--- This doesn't change
userCar.title = 'some other thing'; // <--- This changes
await userCar.save();
} else {
userCar = await UserCars.create({
userId: 20,
title: 'something'
});
}
The problem is, the title is being updated but the userId is not.

Answer 1

(I believe) this is due to constraints, you cannot use instance method to update FK value.
You need to use M-N association functions, or otherwise you could use raw SQL.
const car = await Car.findByPk(10);
const user = await User.findByPk(newValue);
// This also takes care of deleting the old associations
await car.setUsers(user, {
through: {'title': 'new value'}
});
I hope the upsert function is implemented in the future.
ref: https://github.com/sequelize/sequelize/issues/11836