Angular 2：将服务注入另一个服务。 （没有提供者错误）

Question

I want to inject a service to another service:

@Injectable()

export class Dispatcher {
}


@Injectable()

export class TodoStore {

    constructor(@Inject(Dispatcher) dispatcher:Dispatcher){ 

    }
}

But I always get Error: No provider for Dispatcher!

Thanks.

Answer 1

You need to provide your service somewhere. Please refer to angular2 docs

You could provide it in the bootstrap method:

bootstrap(AppComponent,[TodoStore,Dispatcher]);

or the app component:

@Component({
    ...
      providers:[TodoStore,Dispatcher]
}
...

Or in any other component, depending on your needs.

Also, you don't need to @Inject(Dispatcher) in the constructor. It's basically the same as

constructor(dispacher:Dispatcher){
}

Oh yeah, welcome to SO :)

Answer 2

Thank for the reply.

Since it is not a Component, the @Component(...) solution does not apply.

bootstrap(AppComponent,[TodoStore,Dispatcher]); 

solution works. But that makes this main.ts a central place.

Answer 3

A providers array is available in @NgModule. You can provide your service by declaring your service in that array.

@NgModule({
    declarations:[...],
    imports:[...],
    providers: [MyCustomService],
    bootstrap:[AppComponent]
})

Answer 4

Try this:

myMainService.ts

import { myOtherService } from 'myOtherService';

export class myMainService {
 constructor() {
   let myOtherService = new myOtherService();
 }
}

myOtherService.ts

export class myOtherService {
    constructor() {
        console.log('service was imported');
    }
}