Sequelize column region.region_id does not exist error

What am i missing? any help is appreciated. Thanks

facility migration file

await queryInterface.createTable("facility", { id: { allowNull: false, autoIncrement: true, primaryKey: true, type: Sequelize.INTEGER, }, name: { allowNull: false, type: Sequelize.STRING(256), }, address: { allowNull: false, type: Sequelize.STRING(256), }, region_id: { type: Sequelize.BIGINT, references: { model: "region", key: "id", }, }, } 

facility model file

sequelize.define( "facility", { id: { allowNull: false, autoIncrement: true, primaryKey: true, type: DataTypes.INTEGER, }, name: { allowNull: false, type: DataTypes.STRING(256), }, address: { allowNull: false, type: DataTypes.STRING(256), }, region_id: { type: DataTypes.BIGINT, } }) Region.belongsTo(Facility, { foreignKey: "region_id", }); Facility.hasOne(Region, { foreignKey: "region_id", }); 

Executing (default): SELECT "facility"."id", "facility"."name", "facility"."address", "facility"."region_id", "region"."id" AS "region.id", "region"."name" AS "region.name", "region"."region_id" AS "region.region_id" FROM "facility" AS "facility" LEFT OUTER JOIN "region" AS "region" ON "facility"."id" = "region"."region_id"; column region.region_id does not exist error 

I tried this association and it works, but I don't know how it works.

Facility.belongsTo(Region, { foreignKey: "region_id", }); Region.hasOne(Facility, { foreignKey: "region_id", });