How do I inject an AngularJS service in an Angular 5 component? - angularjs

Question

I'm migrating an AngularJS project to Angular 5 using ngUpgrade but I'm running into a problem when trying to inject an AngularJS service in one of my new components.
I followed Angular's upgrade guide and created a serviceProvider that uses the $injector (see code below) but I keep getting this error:
core.js:1449 ERROR Error: Uncaught (in promise): Error: Trying to get the AngularJS injector before it being set.
I suspect I need to use forwardRef somewhere to fix this, but I'm unable to find out how and where (and why).
Following the example of the upgrade guide I created a serviceProvider as follows:
ajs-upgraded-providers.ts:
// The AngularJS service I want to use
import { AuthenticationService } from '../ajs/services/authentication.service';
export function authenticationServiceFactory($injector) {
return $injector.get('authentication');
}
export const authenticationServiceProvider = {
provide: AuthenticationService,
useFactory: authenticationServiceFactory,
deps: ['$injector']
};
Then I provide that to the app's NgModule:
app.module.ts:
#NgModule({
declarations: [
AppComponent
],
imports: [
BrowserModule,
UpgradeModule,
],
providers: [
authenticationServiceProvider,
],
bootstrap: [
AppComponent,
],
})
export class AppModule {
}
I bootstrap that module using ngUpgrade:
main.ts
import { platformBrowserDynamic } from '#angular/platform-browser-dynamic';
import { UpgradeModule } from '#angular/upgrade/static';
import { AppModule } from './app/app.module';
import { environment } from './environments/environment';
// Import our AngularJS module
import '../ajs/app';
platformBrowserDynamic()
.bootstrapModule(AppModule)
.then(platformRef => {
// Use the upgrade module to bootstrap the hybrid
const upgrade = platformRef.injector.get(UpgradeModule) as UpgradeModule;
upgrade.bootstrap(document.documentElement, ['myAngularJSApp']);
});
If I understand correctly, this should allow me to directly inject the AngularJS service into my component like so:
login.component.ts
import { Component } from '#angular/core';
import { AuthenticationService } from '../ajs/services/authentication.service';
#Component({
selector: 'my-login-page',
templateUrl: './login-page.component.html'
})
export class LoginPageComponent {
constructor(private authenticationService: AuthenticationService) {
console.log('authentication', authenticationService);
}
}
Can I do anything to simplify this even more? I tried to follow the upgrade guide as closely as possible, so why doesn't this work?

Answer 1

You need to add
providers: [AuthenticationService]
in Component declaration, like this:
import { Component } from '#angular/core';
import { AuthenticationService } from '../ajs/services/authentication.service';
#Component({
selector: 'my-login-page',
templateUrl: './login-page.component.html',
providers: [AuthenticationService]
})
export class LoginPageComponent {
constructor(private authenticationService: AuthenticationService) {
console.log('authentication', authenticationService);
}
}