Custom Sequelize Datataype

[devin-efw]

How can we define a custom sequelize datatype?

Sequelize is automatically converting the date to include time zone adjustments. Because of this, inserts into the mssql DB are failing.

I would like to define a datatype to override the stringify method for the Date datatype. Doing so, following the sequelize documentation, I'm unable to override the method (https://sequelize.org/docs/v6/other-topics/extending-data-types/) is not working properly.

[devin-efw]

Working example:

import { DataTypes, Sequelize, Utils } from "sequelize";

const DATE = DataTypes.DATE.prototype.constructor;

export class MSSQLDATE extends DATE {
    constructor(length: any) {
        super(length);
    }

    // Method to convert to SQL representation
    toSql() {
        return "DATE";
    }

    // Method to stringify date for DB
    stringify(date: Date, options: object) {
        return this._applyTimezone(date, options).format('YYYY-MM-DD HH:mm:ss.SSS');
    }
}

export function initCustomDatatypes() {
    // Apply classToInvokable transformation
    const invokableMSSQLDATE = Utils.classToInvokable(MSSQLDATE);

    // Add key property
    MSSQLDATE.prototype.key = 'MSSQLDATE';

    //@ts-ignore
    // Expose the class through Sequelize and DataTypes
    Sequelize.MSSQLDATE = DataTypes.MSSQLDATE = invokableMSSQLDATE;
};

Make sure this code is executed before sequelize is initialized. I imported and called the initCustomDatatatypes function in a utilities database mixin. I imported and used the MSSQLDATE class as a datatype type in the sequelize model file.