How to define the possible values of a string in an iterface from an object?

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I have that class Item:

class Item {
  nome: string;
  idade: number;
}

And that interface ConfItem:

interface ConfItem<TypeItem> {
  titulo: string;
}

How do I make for the title in ConfItem accepted only as a string value keys of Item which is received by TypeItem?

I need something like this:

interface ConfItem<TypeItem> {
  titulo: 'nome' | 'idade' 
}

But it has to be dynamic, because ConfItem will be generic, and therefore can receive any TypeItem.

javascript typescript

1 answer

3


You can use the keyof, that returns a Union type of strings containing all object keys.

Then you’d have something like:

interface ConfItem<TypeItem> {
  titulo: keyof TypeItem 
}

See the example above on Typescript playground.

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