An interface cannot be exported in an angular 2 module?

Question

I tried to export an interface in a NgModule-declaration and export and getting this error already in the editor (Visual Studio Code): [ts] \'MyInterface\' only refers

Answer 1

Well actually you can export an interface, but not the way you are trying to do.

First generate interfaces.ts file by typing

ng g interface <interface_name>

Example of interface file:

export interface Auction{ $key?:string; $auctioneer:string;  ... }
export interface Item{ $key?:string; condition?:string; description?:string; ...}
export interface Bid{  $key?:string;  amount:number;  auction:string; ...}

After modifying the file to your needs you can import just one, all or chosen interfaces like this:

import { Auction } from './interfaces';

or

import * as interfaces from './interfaces'; 
// then you have to call interfaces.Auction

If per chance you know how to share interfaces globally pls. let me know here: Angular how to share interfaces across the app

Answer 2

You cannot export an interface. You can only export:

1. Other modules
2. Components
3. Directives
4. Pipes

NgModule is an angular concept and should not be confused with a typescript module. To make a third party, who uses your module, able to use your interface, you should create a .d.ts definition file with your module.

If you want to use a interface inside another NgModule of yours, you should just use:

import {InterfaceName} from 'path/to/ngmodule/to/interface';

Also, do not put an interface in the declarations array, this is only used for pipes/components/directives.

If you want your interface to be usable outside of an library, you should add it to the export of your index.ts:

export {InterfaceName} from 'path/to/ngmodule/to/interface';