How can I have a Sequelize composite key a (non-unique, unique) pair and then use it to map associations? - express

Question

I have these relations in my SQL database. There are two entity types A and B. These entities are owners of a resource and I manage this via a mapping table. The relations are:
Entity A has one or more Owner entries.
Entity B has one or more Owner entries.
Each Owner entry has zero or one Entity A entry.
Each Owner entry has zero or one Entity B entry.
Each Resource has zero or more owners.
Each Owner entry tracks one resource.
I am using this to model individuals and groups owning a resource. The problem is when I go to use the ORM it complains that I have not given an association between Owners and Entities. I'm not really sure how to do this with Sequelize. What I would like to do is have a composite key like so:
(entity_type, entity_id)
where entity_type is from enum (EntityA, EntityB) and entity_id is an id corresponding to a record in either of those tables. In this way I can guarantee that the composite key is unique. But again, I'm not really sure how I can implement this via Sequelize.

Answer 1

While make associate, we can use where condition as below code.
Model : Owner.js
"use strict";
const { Model } = require("sequelize");
module.exports = (sequelize, DataTypes) => {
class Owner extends Model {
static associate(models) {
// define association here
this.belongsTo(models.EntityA, {
foreignKey: "entity_id",
as: "A",
where: { entity_type: 0 }
});
this.belongsTo(models.EntityB, {
foreignKey: "entity_id",
as: "B",
where: { entity_type: 1 }
});
}
}
Owner.init({
entity_type: DataTypes.INTEGER,
entity_id: DataTypes.INTEGER,
}, {
sequelize,
modelName: "Owner"
});
return Owner;
};
db.Owner.findAll({
include: 'A', 'B'
});