从打字稿中的通用类扩展的类扩展

Question

I've got a chain of classes that all use the same constructor in typescript. I'd like to ensure it receives the same class as the object itself.

class Node<T> {
  readonly id: number
  constructor (data: T) {
    Object.assign(this, data)
  }
}

class User extends Node<User> {
  readonly name: string
}

class CoolUser extends User {
  readonly coolness: number
}

const node = new Node({ id: 3 })
const user = new User({ id: 4, name: 'bob' })
const coolUser = new CoolUser({ id: 4, name: 'super cool person', coolness: 7 })

The last line fails type checking since coolness isn't a property of user. I'm set on using the generic class approach but I'm unsure how to define the constructor input types to check properly.

Answer 1

You have to make User generic, too.

class Node<T> {
  readonly id: number;

  constructor(data: T) {
    Object.assign(this, data);
  }
}

class User<T> extends Node<T> {
  readonly name: string;
}

class CoolUser extends User<CoolUser> {
  readonly coolness: number;
}