Global instance of provider in Ionic 3

Question

I have a provider that has to be always up when the app is running to watch for the network connection status.

So according to that tutorial I have added the class to my app.module.ts file to make it a global instance. So as far as I understand it, the service should be up when the app initializes it's root component (thus app.module.ts).

Problem: The provider gets not called until a specific page of the app imports and uses it.

In the mentioned tutorial the provider is imported like that:

ionicBootstrap(MyApp, [TestProvider]);

Unfortunately that does not work for me. That post says that this quite new tutorial is outdated.

Question: How could I use providers in Ionic 3 that they are available as one instance after launching the application?

My app.module.ts:

import { NetworkConnectionProvider } from '../providers/networkconnection/networkconnection';
// (...)

@NgModule({
  declarations: [
    MyApp,
    // (...)
  ],
  imports: [
    BrowserModule,
    HttpModule,
    IonicModule.forRoot(MyApp),
    ionicGalleryModal.GalleryModalModule,
  ],
  bootstrap: [
    IonicApp
  ],
  entryComponents: [
    MyApp,
    // (...)
  ],
  providers: [
    // (...)
    NetworkConnectionProvider
  ]
})
export class AppModule {}

My provider:

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';
import { Network } from '@ionic-native/network';


@Injectable()
export class NetworkConnectionProvider {
  private TAG = "NetworkConnectionProvider ";

  private isConnectedToInternet: Boolean;

  constructor(
    public http: Http,
    public network: Network
    ) {

    this.isConnectedToInternet = true;

    let disconnectSubscription = this.network.onDisconnect().subscribe(() => {
      console.log(this.TAG + 'network was disconnected.');
      this.isConnectedToInternet = false;
    });

    // watch network for a connection
    let connectSubscription = this.network.onConnect().subscribe(() => {
      console.log('network connected!');
      this.isConnectedToInternet = true;

      // We just got a connection but we need to wait briefly
      // before we determine the connection type. Might need to wait.
      // prior to doing any api requests as well.
      setTimeout(() => {
        if (this.network.type === 'wifi') {
          console.log(this.TAG + 'wifi connection available');
        }
      }, 3000);
    });

    console.log('Hello NetworkConnectionProvider');
  }

  public subscribeOnConnect() {
    return this.network.onConnect();
  }

  public isConnected(): Boolean{
    return this.isConnectedToInternet;
  }

  public getConnectionType(): string {
    return this.network.type;
  }

}

Answer 1

To achieve that the app creates an instance of a provider on launching (what makes sense for a network provider that watches the network status ) simply add the provider to the app.module.ts

  providers: [
    NetworkConnectionProvider
  ]

After that add it to the constructor of app.component.ts

constructor(
    platform: Platform,
    statusBar: StatusBar,
    splashScreen: SplashScreen,
    private sideMenuService: SideMenuService,
    network: NetworkConnectionProvider
  ) {

    platform.ready().then(() => {
      // Okay, so the platform is ready and our plugins are available.
      // Here you can do any higher level native things you might need.
      statusBar.styleDefault();
      splashScreen.hide();
    });

    // other stuff
  }

Every time that provider is imported and used later on in the app it will be the same instance.

Answer 2

You have to call that provider at least once, Call that provider in your home.ts file

import { NetworkConnectionProvider } from '../Your-Path';

constructor(public navCtrl: NavController, public netprovider : NetworkConnectionProvider ) {
   netprovider.activateNetwork();
}

create a activateNetwork() function in your provider.

In your provider file:

activateNetwork(){
   let disconnectSubscription = this.network.onDisconnect().subscribe(() => {
  console.log(this.TAG + 'network was disconnected.');
  this.isConnectedToInternet = false;
});

// watch network for a connection
let connectSubscription = this.network.onConnect().subscribe(() => {
  console.log('network connected!');
  this.isConnectedToInternet = true;

  // We just got a connection but we need to wait briefly
  // before we determine the connection type. Might need to wait.
  // prior to doing any api requests as well.
  setTimeout(() => {
    if (this.network.type === 'wifi') {
      console.log(this.TAG + 'wifi connection available');
    }
  }, 3000);
});

}

Answer 3

You have done it wrong with latest Ionic 3 and CLI.It was an old method and now outdated.

Hope you're using latest CLI.Then it is automatic mostly.

ionic generate provider SubscribeTopic

It'll automatically add SubscribeTopic into providers array in the app.module.ts

Note: This is just an example.Please adjust it according to your use case.

app.module.ts

providers: [
  //other providers here
  SubscribeTopic //here
]

After that, you need to inject it into your page as shown below.

yourPage.ts

constructor(private navCtrl: NavController, private subscribeTopic : SubscribeTopic ) {

  }

That is it.You can refer this article too.