Define global constants

Question

In Angular 1.x you can define constants like this:

angular.module('mainApp.config', [])     .constant('API_ENDPOINT', 'http://127.0.0.1:6666/api/') 

What would be the equivalent in Angular (with TypeScript)?

I just don't want to repeat the API base url over and over again in all my services.

Answer 1

Below changes works for me on Angular 2 final version:

export class AppSettings {    public static API_ENDPOINT='http://127.0.0.1:6666/api/'; } 

And then in the service:

import {Http} from 'angular2/http'; import {Message} from '../models/message'; import {Injectable} from 'angular2/core'; import {Observable} from 'rxjs/Observable'; import {AppSettings} from '../appSettings'; import 'rxjs/add/operator/map';  @Injectable() export class MessageService {      constructor(private http: Http) { }      getMessages(): Observable<Message[]> {         return this.http.get(AppSettings.API_ENDPOINT+'/messages')             .map(response => response.json())             .map((messages: Object[]) => {                 return messages.map(message => this.parseData(message));             });     }      private parseData(data): Message {         return new Message(data);     } } 

Answer 2

The solution for the configuration provided by the angular team itself can be found here.

Here is all the relevant code:

1) app.config.ts

import { OpaqueToken } from "@angular/core";  export let APP_CONFIG = new OpaqueToken("app.config");  export interface IAppConfig {     apiEndpoint: string; }  export const AppConfig: IAppConfig = {         apiEndpoint: "http://localhost:15422/api/"     }; 

2) app.module.ts

import { APP_CONFIG, AppConfig } from './app.config';  @NgModule({     providers: [         { provide: APP_CONFIG, useValue: AppConfig }     ] }) 

3) your.service.ts

import { APP_CONFIG, IAppConfig } from './app.config';  @Injectable() export class YourService {      constructor(@Inject(APP_CONFIG) private config: IAppConfig) {              // You can use config.apiEndpoint now     }    } 

Now you can inject the config everywhere without using the string names and with the use of your interface for static checks.

You can of course separate the Interface and the constant further to be able to supply different values in production and development e.g.