Custom datatype not working

What are you doing?

// Custom Type File
import Big from "big.js";

export default function sequelizeAdditions(Sequelize) {

    const DataTypes = Sequelize.DataTypes;

    /*
     * Create new types
     */
    class BIGJS extends DataTypes.DECIMAL {
        public static parse(value) {
            return new Big(value);
        }

        private _precision: number;
        private _scale: number;

        constructor(precision: number, scale: number) {
            super();

            this._precision = precision;
            this._scale = scale;
        }

        public toSql() {
            if (this._precision || this._scale) {
                return `DECIMAL(${[this._precision, this._scale].filter(this.identity).join(",")})`;
            }

            return "DECIMAL";
        }

        // Optional, validator function
        public validate(value, options) {
            if (value instanceof Big) {
                return true;
            } else {
                return false;
            }
        }
    }

    DataTypes.BIGJS = BIGJS;

    // Mandatory, set key
    DataTypes.BIGJS.prototype.key = DataTypes.BIGJS.key = "BIGJS";

    // For convenience
    // `classToInvokable` allows you to use the datatype without `new`
    Sequelize.BIGJS = Sequelize.Utils.classToInvokable(DataTypes.BIGJS);
}

// Connection File
import { Sequelize } from "sequelize";
import BigJsCol from "./types/BigJsColumn";

BigJsCol(Sequelize);

const sequelize = new Sequelize(...);

// Model File
MyModel.init({
    id: {
        type: DataTypes.INTEGER.UNSIGNED,
        autoIncrement: true,
        primaryKey: true,
    },
    amount: new DataTypes.BIGJS(13, 4)
}, {
    sequelize: Connection,
    tableName: "MyModel",
});

// Simple Query
await MyModel.findAll();

To Reproduce Steps to reproduce the behavior:

1. Defined models, and get everything wired up
2. Run simple query
3. Result for the field amount is not wrapped in a BigJs object

What do you expect to happen?

I would like the result coming back from the database to be wrapped

What is actually happening?

It is just returning a number 😦

Environment

Dialect:

• mysql
• postgres
• sqlite
• mssql
• any Dialect mysql2 version: 1.6.5 Database version: 5.7.26 Sequelize version: 5.9.3 Node Version: 12.x OS: Mac OS 10.14.5 If TypeScript related: TypeScript version: 3.5.3 Tested with latest release:
• No
• Yes, specify that version:

[mcuelenaere]

The issue lays with classToInvokable, which doesn’t allow access to the actual constructor. The following code shows how we worked around that:

const DataTypes = require('sequelize/lib/data-types');
const { classToInvokable } = require('sequelize/lib/utils/classToInvokable');

// since DataTypes.ABSTRACT is wrapped with classToInvokable(), we can't get to
// the actual class directly, so use this indirection
const ABSTRACT = DataTypes.ABSTRACT.prototype.constructor;

class Custom extends ABSTRACT {
  static key = 'CUSTOM';

  toSql() {
    return 'BIGINT(20) UNSIGNED';
  }

  ...
}
DataTypes.CUSTOM = classToInvokable(Custom);

[github-actions[bot]]

This issue has been automatically marked as stale because it has been open for 14 days without activity. It will be closed if no further activity occurs within the next 14 days. If this is still an issue, just leave a comment or remove the “stale” label. 🙂