Angular no provider for NameService

Question

I've got a problem loading a class into an Angular component. I've been trying to solve it for a long time; I've even tried joining it all in a single file. What I have is:

Application.ts

/// <reference path="../typings/angular2/angular2.d.ts" />

import {Component,View,bootstrap,NgFor} from "angular2/angular2";
import {NameService} from "./services/NameService";

@Component({
    selector:'my-app',
    injectables: [NameService]
})
@View({
    template:'<h1>Hi {{name}}</h1>' +
    '<p>Friends</p>' +
    '<ul>' +
    '   <li *ng-for="#name of names">{{name}}</li>' +
    '</ul>',
    directives:[NgFor]
})

class MyAppComponent
{
    name:string;
    names:Array<string>;

    constructor(nameService:NameService)
    {
        this.name = 'Michal';
        this.names = nameService.getNames();
    }
}
bootstrap(MyAppComponent);

services/NameService.ts

export class NameService {
    names: Array<string>;
    constructor() {
        this.names = ["Alice", "Aarav", "Martín", "Shannon", "Ariana", "Kai"];
    }
    getNames()
    {
        return this.names;
    }
}

I keep getting an error message saying No provider for NameService.

Can someone help me spot the issue with my code?

Octroi

as of Alpha 42: @Component({ providers: [NameService] }) – Schaffer

Answer 1

You have to use providers instead of injectables

@Component({
    selector: 'my-app',
    providers: [NameService]
})

Complete code sample here.

Redingote

An update for future googlers: using providers works on the latest beta (beta 0). – Scotticism

@Scotticism both bindings and providers work - is this temporary or are they just doing the same internally – Applecart

@Applecart hmm they may have changed it in the latest beta - in beta.0 I couldn't get it to work with bindings – Scotticism

@Scotticism it seems like providers made it's way into the release also. – Grimsley

what if the service is used from another service? i added it to module providers which i thought would make it available globally, but still getting that error – Subrogate

Answer 2

In Angular 2 there are three places you can "provide" services:

1. bootstrap
2. root component
3. other components or directives

"The bootstrap provider option is intended for configuring and overriding Angular's own preregistered services, such as its routing support." -- reference

If you only want one instance of NameService across your entire app (i.e., Singleton), then include it in the providers array of your root component:

@Component({
   providers: [NameService],
   ...
)}
export class AppComponent { ... }

Plunker

If you would rather have one instance per component, use the providers array in the component's configuration object instead:

@Component({
   providers: [NameService],
   ...
)}
export class SomeOtherComponentOrDirective { ... }

See the Hierarchical Injectors doc for more info.

Carrousel

This is a really good answer. It further explains the differences between declaring the service in the root component versus declaring in other child components. – Clarethaclaretta

Answer 3

As of Angular 2 Beta:

Add @Injectable to your service as:

@Injectable()
export class NameService {
    names: Array<string>;

    constructor() {
        this.names = ["Alice", "Aarav", "Martín", "Shannon", "Ariana", "Kai"];
    }

    getNames() {
        return this.names;
    }
}

and to your component config add the providers as:

@Component({
    selector: 'my-app',
    providers: [NameService]
})

Elevator

Answer 4

You should be injecting NameService inside providers array of your AppModule's NgModule metadata.

@NgModule({
   imports: [BrowserModule, ...],
   declarations: [...],
   bootstrap: [AppComponent],
   //inject providers below if you want single instance to be share amongst app
   providers: [MyService]
})
export class AppModule {

}

If you want to create an Dependency for particular component level without bothering about state of your application, then you can inject that dependency on component providers metadata option like accepted @Klass answer shown.

Roose

I have tried adding a service in app.module.shared.ts in @NgModule section : providers: [DataManagerService] but still get the error : Error: No provider for DataManagerService! – Memorialist

@Memorialist are you injecting your service in correct Module? and does DataManagerService has @Injectable decorator over it? – Roose

Answer 5

Shockingly, the syntax has changed yet again in the latest version of Angular :-) From the Angular 6 docs:

Beginning with Angular 6.0, the preferred way to create a singleton services is to specify on the service that it should be provided in the application root. This is done by setting providedIn to root on the service's @Injectable decorator:

src/app/user.service.0.ts

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root',
})
export class UserService {
}

Guilbert

Answer 6

You should be injecting NameService inside providers array of your AppModule's NgModule metadata.

@NgModule({
   providers: [MyService]
})

and be sure import in your component by same name (case sensitive),becouse SystemJs is case sensitive (by design). If you use different path name in your project files like this:

main.module.ts

import { MyService } from './MyService';

your-component.ts

import { MyService } from './Myservice';

then System js will make double imports

Yatzeck

Excellent! When using barrels to group imports I encountered this error. Your SystemJS tip helped me :) – Lauranlaurance

Answer 7

In Angular v2 and up it is now:

@Component({ selector:'my-app', providers: [NameService], template: ... })

Postmeridian

Answer 8

Angular 2 has changed, here is what the top of your code should look like:

import {
  ComponentAnnotation as Component,
  ViewAnnotation as View, bootstrap
} from 'angular2/angular2';
import {NameService} from "./services/NameService";

@Component({
  selector: 'app',
  appInjector: [NameService]
})

Also, you may want to use getters and setters in your service:

export class NameService {
    _names: Array<string>;
    constructor() {
        this._names = ["Alice", "Aarav", "Martín", "Shannon", "Ariana", "Kai"];
    }
    get names() {
        return this._names;
    }
}

Then in your app you can simply do:

this.names = nameService.names;

I suggest you go to plnkr.co and create a new Angular 2 (ES6) plunk and get it to work in there first. It will set everything up for you. Once it's working there, copy it over to your other environment and triage any issues with that environment.

Corrigan

Answer 9

The error No provider for NameService is a common issue that many Angular2 beginners face.

Reason: Before using any custom service you first have to register it with NgModule by adding it to the providers list:

Solution:

@NgModule({
    imports: [...],
    providers: [CustomServiceName]
})

Flower

Answer 10

You could also have the dependencies declared in the bootstrap-command like:

bootstrap(MyAppComponent,[NameService]);

At least that's what worked for me in alpha40.

this is the link: http://www.syntaxsuccess.com/viewarticle/dependency-injection-in-angular-2.0

Bezanson

Answer 11

Hi , You can use this in your .ts file :

first import your service in this .ts file:

import { Your_Service_Name } from './path_To_Your_Service_Name';

Then in the same file you can add providers: [Your_Service_Name] :

 @Component({
      selector: 'my-app',
      providers: [Your_Service_Name],
      template: `
        <h1>Hello World</h1> `   
    })

Pickwickian

Answer 12

Add it to providers not injectables

@Component({
    selector:'my-app',
    providers: [NameService]
})

Strophanthus

Answer 13

In Angular you are able to register a service in two ways:

1. Register a service in module or root component

Effects:

• Available into all components
• Available on lifetime application

You should take care if you register a service into a lazy loaded module:

• The service is available only into components declared into that module

• The service will be available on lifetime application only when the module is loaded

2. Register a service into any other application component

Effects:

• Will be injected a separate instance of the Service into the component

You should take care if you register a service into any other application component

• The instance of the injected service will be available only into the component and all of its children.

• The instance will be available on the component lifetime.

Catiline

Answer 14

add your service to providers[] array in app.module.ts file. Like below

// here my service is CarService

app.module.ts

import {CarsService} from './cars.service';

providers: [CarsService] // you can include as many services you have 

Hagy

Answer 15

You need to add it to providers array, which includes all depency on your component.

Look at this section in angular documentation:

Registering providers in a component

Here's a revised HeroesComponent that registers the HeroService in its providers array.

import { Component } from '@angular/core';

import { HeroService } from './hero.service';

@Component({
  selector: 'my-heroes',
  providers: [HeroService],
  template: `
  <h2>Heroes</h2>
  <hero-list></hero-list>
  `
})
export class HeroesComponent { }

When to use NgModule versus an application component

On the one hand, a provider in an NgModule is registered in the root injector. That means that every provider registered within an NgModule will be accessible in the entire application.

On the other hand, a provider registered in an application component is available only on that component and all its children.

Here, the APP_CONFIG service needs to be available all across the application, so it's registered in the AppModule @NgModule providers array. But since the HeroService is only used within the Heroes feature area and nowhere else, it makes sense to register it in the HeroesComponent.

Also see "Should I add app-wide providers to the root AppModule or the root AppComponent?" in the NgModule FAQ.

So in your case, simply change injectables to providers like below:

@Component({
  selector: 'my-app',
  providers: [NameService]
})

Also in the new versions of Angular, @View and some other stuffs gone.

For more info ,visit here.

Sizeable

Answer 16

Blockquote

Registering providers in a component

Here's a revised HeroesComponent that registers the HeroService in its providers array.

import { Component } from '@angular/core';

import { HeroService } from './hero.service';

@Component({
  selector: 'my-heroes',
  providers: [HeroService],
  template: `
  `
})
export class HeroesComponent { }

Rebroadcast

Answer 17

Angular2 requires you to declare all the injectables in bootstrap function call. Without this your service is not an injectable object.

bootstrap(MyAppComponent,[NameService]);

Clime

This is not quite correct. We can include the service in bootstrap(), or in the providers array in the component's configuration object. If it is included in the providers array, we get one instance per bound component. See the Hierarchical Injectors doc for more info. – Carrousel

yes as said by @MarkRajcok also we provide only those services at the time of bootstrap which one's we have to use throughout the whole app. by doing so we did't need to inject every time in the provider because it will create instance for the every component. – Modification

Answer 18

Add @Injectable to your service as:

export class NameService {
    names: Array<string>;

    constructor() {
        this.names = ["Alice", "Aarav", "Martín", "Shannon", "Ariana", "Kai"];
    }

    getNames() {
        return this.names;
    }
}

and in your component add the providers as:

@Component({
    selector: 'my-app',
    providers: [NameService]
})

or if you want to access your service all over the application you can pass in app provider

Bedcover