Typescript - interface where property takes itself as a parameter

Question

I have a type where one of the properties is a class that takes that type as a parameter

interface Type<P extends {}> {
  name: string;
  props: P;
  field: new(type: Type<P>) => { ... };
}

// Define some Types
interface AllTypes {
  Foo: Type<{}>;
  Bar: Type<{
    foo: string;
    bar: number
  }>
}
type SomeType = AllTypes[keyof AllTypes];

I have a function that takes a SomeType and tries to instantiate its field, but I get an error

function f(type: SomeType) {
  return new type.field(type);  // Error
}

Changing Type.field to new(type: SomeType) => ... will solve this error, but will create further errors down the line:

class Field<T extends SomeType> {
  type: T;
  constructor(type: T) {
    this.type = type;
  }
}
declare class FooField extends Field<AllTypes['Foo']> {}
declare class BarField extends Field<AllTypes['Bar']> {}

const fields: SomeType[] = [
  {
    name: 'foo',
    props: {},
    field: FooField,
  },
  {
    name: 'bar',
    props: {  // This error is expected and desired
      foo: 0,
      bar: 'hi',
    },
    field: BarField,  // Error
  },
];

Maciej Sikora · Accepted Answer · 2020-03-12 22:10:50Z

1

I think this is what you look for:

interface Type<P extends {}> {
  name: string;
  props: P;
  field: new<T extends Type<any>>(type: T) => { };
}

answered Mar 12, 2020 at 22:10

Maciej Sikora

20.3k4 gold badges52 silver badges50 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Typescript - interface where property takes itself as a parameter

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related