Problem coding a weak entity in sequelize - mysql

Question

I am creating a cinema application. I have modeled the database on mySql but I am having trouble migrating it to Sequelize. I have followed the documentation but I am getting a lot of different errors.
I have tried using associations and indexes (as it should be). This is the model I am trying to make.
OCCUPIED_SEATS is composed of only two foreign keys and both make a unique index.
OCCUPIED_SEATS:
const SEATS = require("./Seats");
const SCREENING = require("./Screening");
const OCCUPIED_SEATS = sequelize.define("OCCUPIED_SEATS", {
//SEATS_ID
//SCREENING_ID
},
{
indexes: [
{
unique: true,
fields: [SEAT_ID, SCREENING_ID]
}
],
underscored: true
}
);
module.exports = OCCUPIED_SEATS;
SEATS:
const OCCUPIED_SEATS = require("./Occupied_Seats");
const SEATS = sequelize.define("SEATS", {
SEATS_ID: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull: false,
autoIncrement: true
},
ROW: {
type: Sequelize.STRING,
allowNull: false,
},
COLUMN: {
type: Sequelize.INTEGER,
allowNull: false
},
},
{
underscored: true
}
);
SEATS.hasMany(OCCUPIED_SEATS, {foreignKey: 'SEAT_ID'})
module.exports = SEATS;
SCREENING:
const OCCUPIED_SEATS = require("./Occupied_Seats");
const SCREENING = sequelize.define("SCREENING", {
SCREENING_ID: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull: false,
autoIncrement: true
},
SCREENING_START_TIME: {
type: Sequelize.TIME,
allowNull: false,
},
DATE: {
type: Sequelize.DATE,
allowNull: false
}
},
{
underscored: true,
indexes: [
{
unique: true,
fields: [ROOM_ID, SCREENING_START_TIME, DATE]
}
]
}
);
SCREENING.hasMany(OCCUPIED_SEATS, {foreignKey: 'SCREENING_ID'});
module.exports = SCREENING;
The error I am getting when I try this is:
[💻] Error: SEATS.hasMany called with something that's not a subclass of Sequelize.Model
How should I code the model?

Answer 1

Looks like in the new version of Sequelize you have to define your models through Sequelize.Model type:
class Seats extends Sequelize.Model {}
Seats.init({
id: {
type: Sequelize.INTEGER,
primaryKey: true,
allowNull: false,
autoIncrement: true
},
row: {
type: Sequelize.STRING,
allowNull: false,
},
...
});
module.exports = Seats;
And then somewhere else:
Seats.hasMany(OccupiedSeatc, {foreignKey: 'SEAT_ID'})
See model definition docs and accociation docs.