How do I export services in a module?

Question

How can I export a service from a module in angular 2?

The idea is that when I import into another component, I want the import to be agnostic of the actual service location, it should be the repsonsibility of the module to manage that

Core.module.ts:

import {
NgModule,
Optional, SkipSelf } from '@angular/core';
import { CommonModule } from '@angular/common';

import { MyApi } from './Api/myApi.service';

import { AuthenticationModule } from './authentication/authentication.module';

@NgModule({
imports: [
    CommonModule,
    AuthenticationModule
],
providers: [
    MyApi
],
exports: [MyApi, AuthenticationModule]
})
export class CoreModule {
constructor( @Optional() @SkipSelf() parentModule: CoreModule) {
    if (parentModule) {
    throw new Error(
        'CoreModule is already loaded. Import it in the AppModule only');
    }
}

}

App.component.ts:

import { Router, ActivatedRoute } from '@angular/router';
import { Component, ViewContainerRef, OnInit } from '@angular/core';

import { MyApi } from 'core.module'; //i want this to be the core module import, not './core/api/myApi.service'

@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
    constructor ( public service: MyApi) {
        service.doStuff()
    }
}

But in the code example above, it tells me that MyApi isn't exported by Core.module.

This is slightly pseudo-code, so excuse the small errors I've made :)

Answer 1

There's two things you can do to make your imports more concise:

1. You can export everything from your entry point file (by convention is often called index.ts) and later import any class you've exported from that file:

   import { NgModule } from '@angular/core';
   import { ApiService } from 'path/to/api.service';
   @NgModule({ ... })
   export class CoreModule {}
   export * from 'path/to/api.service';
   

   This way you can then import both CoreModule and ApiService from the same route like this:

   import { CoreModule, ApiService } from 'path/to/core.module;'
   

   So you have a common entry point for all your module dependencies.

2. If your module is deeply nested, or you want to import it from a location that might end up in going back and forth a few directories, you can always create an alias for that path in your main tsconfig.json file, under compilerOptions.paths:

   {
     "compilerOptions": {
       // ...
       "paths": {
         "@app-core": ["app/path/to/deeply/nested/core.module"]
       }
     }
   }
   

   And then use that alias instead:

   import { CoreModule, ApiService } from '@app-core'