Keyof inferring string | number when key is only a string

Question

I define an AbstractModel like so:

export interface AbstractModel {
   [key: string]: any
}

Then I declare the type Keys

Answer 1

I have faced similar problem. I resolved it by enforcing key to be string:

export type Keys = keyof AbstractModel & string;

Other option would be to convert key to string: test.toString().toLowercase()