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typescriptsequelize.js

Add Static Method to Sequelize Model Abstract Class with Typescript

When working with Sequelize, I found it helpful to add static methods to all Models. In Javascript I would simply assign the method in the following way:

const { Model } = require('sequelize)

Model.someStaticMethod = () => {}

However, in Typescript, this will cause an error as someStaticMethod is not defined on the abstract class Model.

Solution

  • In order to get around this, you can create variables within a given namespace, thereby allowing you to augment the class and add static methods.

    // types/sequelize/index.d.ts

import 'sequelize'

declare module 'sequelize' {
  namespace Model {
    let someStaticMethod : function // You can import the actual function definition here.
  }
}

    Now when assigning Model.someStaticMethod = () => {}, Typescript will no longer throw an error.

    Hope this helps someone out!