How to override static variables from inherited derived classes in typescript

Question

I'd like to have the the static implementation of a static method use the derived class's value. For example, in the simple example below, when I call User.findById() I want it to use the overridden tableName User when executing the implementation defined in the base class SqlModel.

How do I make sure that the base classes static tableName uses 'User' and is this the right way of essentially declaring an abstract static property?

class SqlModel {

    protected static tableName:string;

    protected _id:number;
    get id():number {
        return this._id;

    }

    constructor(){

    }

    public static findById(id:number) {
        return knex(tableName).where({id: id}).first();
    }

}

export class User extends SqlModel {

    static tableName = 'User';

    name:string;

    constructor(username){
        this.name = username;
    }
}

And I would get an error saying tablename is not defined, but if I say SqlModel.tableName then it doesn't use the derived classes table name

User.findById(1); //should call the knex query with the tablename 'User'

Answer 1

I managed to get the static like this:

(<typeof SqlModel> this.constructor).tableName

Answer 2

You can use this.tableName:

class SqlModel {
    protected static tableName: string;

    public static outputTableName() {
        console.log(this.tableName);
    }
}

class User extends SqlModel {
    protected static tableName = 'User';
}

User.outputTableName(); // outputs "User"