CODEWITHSUNDEEP
typescripttypescript-generics
jayarjo
jayarjo

Reputation: 16716

How to typesafe an object one of the properties of which might be of different name?

Suppose I want to type an object where I don't know the name of one of properties, but know the type of its value. So it's something like that:

type PagedResponse<T> = {
  Suppliers: Array<T>; // <- this prop might have different name
  nextPageToken: number;
  total: number;
};

Suppliers prop might be of different name - Products or anything else, but it should be of type Array<T>. How do I type something like that? Is it possible to pass the name of that last prop as another argument to the type.

Upvotes: 0

Views: 72

Answers (2)

Jayshree Wagh
Jayshree Wagh

Reputation: 80

You can do something like this

type PagedResponse<T> = {
 [prop: string]: Array<T>; // <- this prop might have different name
 nextPageToken: number;
 total: number;
};

Upvotes: 1

Karol Majewski
Karol Majewski

Reputation: 25790

Try this:

type PagedResponse<T, K extends string = string> = {
  nextPageToken: number;
  total: number;
} & {
    [P in K]: Array<T>;
}

const response: PagedResponse<number, 'Products'> = {
    Products: [1, 2, 3],
    total: 10,
    nextPageToken: 20
}

Upvotes: 1

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