Inject custom service in another service in Angular 2

Question

I want to inject service into another service. I don't have any problems injecting standard angular services (Http, etc.), but I get an exeption when I am trying to inject my own services.

Example:

MyService:

import {Injectable, Inject} from 'angular2/core';
import {AnotherService} from '../../services/another.service';

@Injectable()
export class MyService {
  constructor(Inject(AnotherService) private anotherService: AnotherService) {
    console.log(this.anotherService.get());
  }
}

AnotherService:

import {Injectable} from 'angular2/core';

@Injectable()
export class AnotherService {

   constructor() { }
   get() { return 'hello'); }

}

When I try to use MyService I get EXCEPTION: No provider for AnotherService!

I've tried using constructor(private anotherService: AnotherService), still throws an exception.

Thanks!

Answer 1

You should read the Angular 2 documentation. Your exact issue is explained in the angular docs here: https://angular.io/docs/ts/latest/guide/dependency-injection.html#when-the-service-needs-a-service

You must add your service to a providers array. The only reason you can use Http without doing this is because Ionic puts it on the providers array for you. If you were using vanilla Angular 2 you would still have to add HTTP_PROVIDERS to the providers array.

As a side note, you don't need that Inject in your constructor, you can just do:

constructor(private anotherService: AnotherService) {
  console.log(this.anotherService.get());
}