How to describe an index type with generic values in Typescript?

Question

Is there any way to describe this interface in typescript:

abstract class Entity { /*...*/ }
interface List<A extends Entity> { /*...*/ }

// I want the below interface
interface Collections {
  [name: string]: List<A extends Entity>;
}

The Collections object contains different List objects of classes that extend the Entity class. So the following code doesn't solve my problem:

interface Collections<A extends Entity> {
  [name: string]: List<A>;
}

The above interface serves only for one single class A, I want it to serve multiple classes extend from Entity class.

Thank you!

Drag13 · Accepted Answer · 2020-07-22 11:48:03Z

1

If I caught the idea, this might be the solution?

abstract class Entity { /*...*/ }
class Book extends Entity { title = 'default'; }
class Spoon extends Entity { price = 5; }

interface List<A> { /*...*/ }
interface EntityList extends List<Entity>{}

interface Collections {
  [name: string]: EntityList
}

const t: Collections = {
  'test': [new Book(), new Spoon()]
}

const x = t['test'];

If you don't wont to close type you might do this:

interface Collections<T> {
  [name: string]: List<T>
}

const t: Collections<Entity> = {
  'test': [new Book(), new Spoon()]
}

edited Jul 22, 2020 at 11:48

answered Jul 22, 2020 at 11:18

Drag13

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