Get keys of a Typescript interface as array of strings

Question

I\'ve a lot of tables in Lovefield and their respective Interfaces for what columns they have.
Example:

export interface IMyTable {
  id: number;
  t         


        

Answer 1

Maybe it's too late, but in version 2.1 of typescript you can use key of like this:

interface Person {
    name: string;
    age: number;
    location: string;
}

type K1 = keyof Person; // "name" | "age" | "location"
type K2 = keyof Person[];  // "length" | "push" | "pop" | "concat" | ...
type K3 = keyof { [x: string]: Person };  // string

Doc: https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-1.html#keyof-and-lookup-types

Answer 2

You will need to make a class that implements your interface, instantiate it and then use Object.keys(yourObject) to get the properties.

export class YourClass implements IMyTable {
    ...
}

then

let yourObject:YourClass = new YourClass();
Object.keys(yourObject).forEach((...) => { ... });

Answer 3

This should work

var IMyTable: Array<keyof IMyTable> = ["id", "title", "createdAt", "isDeleted"];

or

var IMyTable: (keyof IMyTable)[] = ["id", "title", "createdAt", "isDeleted"];

Answer 4

You can't do it. Interfaces don't exist at runtime (like @basarat said).

Now, I am working with following:

const IMyTable_id = 'id';
const IMyTable_title = 'title';
const IMyTable_createdAt = 'createdAt';
const IMyTable_isDeleted = 'isDeleted';

export const IMyTable_keys = [
  IMyTable_id,
  IMyTable_title,
  IMyTable_createdAt,
  IMyTable_isDeleted,
];

export interface IMyTable {
  [IMyTable_id]: number;
  [IMyTable_title]: string;
  [IMyTable_createdAt]: Date;
  [IMyTable_isDeleted]: boolean;
}

Answer 5

Can't. Interfaces don't exist at runtime.

workaround

Create a variable of the type and use Object.keys on it

Answer 6

// declarations.d.ts
export interface IMyTable {
      id: number;
      title: string;
      createdAt: Date;
      isDeleted: boolean
}
declare var Tes: IMyTable;
// call in annother page
console.log(Tes.id);