Navigating between tabs in an Ionic Angular app

If your Ionic Angular app has several tabs, you can add voice commands to navigate through the app. In this tutorial, we will use a simple Ionic app with three tabs to demonstrate how to use voice commands to switch between them.

What you will learn

• How to send commands from the voice script to an Ionic Angular app

• How to set up the Alan event listener and handle commands on the app side

• How to navigate between tabs in an Ionic Angular app with voice

What you will need

To go through this tutorial, make sure the following prerequisites are met:

• You have completed the following tutorial: Building a voice assistant for an Ionic Angular app.

• The environment for using the Ionic framework is properly set up. For details, see Ionic documentation.

We will use an example Ionic Angular app provided by Alan. You can also use your own app with several tabs. Make sure you have added the Alan button to the app as described in the previous tutorial.

Step 1: Add voice commands for navigation

We need to add a new command to the Alan script to navigate between tabs with voice. In Alan Studio, open the project and in the code editor, add the following intent:

intent('Go to the $(ORDINAL) tab', p => {
    const availableTabs = new Set([1,2,3]);
    if (availableTabs.has(p.ORDINAL.number)) {
        p.play({command: 'navigation', tabNumber: p.ORDINAL.number});
        p.play(`Opening the ${p.ORDINAL.value} tab`);
    } else {
        p.play('The tab with this number is not found');
    }
});

The user can now give a voice command to go to a specific tab in the app. In the intent, we use the ORDINAL predefined slot. This slot allows us to catch the ordinal number in the user utterance. If the caught number is first, second or third, the navigation command and the tab number will be sent from the voice script to the app. If the voice command contains some other number, Alan will report that such tab is not found.

Step 2: Inject NavController

For this tutorial, we will use NavController to switch between the app tabs. We need to update the Ionic app to inject NavController.

1. In the Ionic app, go to src/app and open the app.component.ts file.

2. At the top of the file, add the following import statement:

   import { Platform, NavController } from '@ionic/angular';
   

3. To constructor of the AppComponent class, add private navCtrl: NavController:

   ...
   export class AppComponent {
       constructor(
           private navCtrl: NavController
       ) {}
   }
   ...
   

   see full source

Step 3: Handle commands on the app side

Now, when we say, for example, Go to the second tab, Alan sends the navigation command and the 2 tab number to the app. We need to handle this command on the app side and make sure the app opens the necessary tab when the command is received. To do this, we will add a handler to the app.

1. In the Ionic app, go to src/app and open the app.component.ts file.

2. In the ngAfterViewInit() method, update the code for the Alan button event listener:

   ngAfterViewInit() {
       this.alanBtnComponent.nativeElement.addEventListener('command', (data) => {
           const commandData = (<CustomEvent>data).detail;
   
           if (commandData.command === 'navigation') {
               /* Call client code that will react to the received command */
               this.navCtrl.navigateForward([`/tabs/tab${commandData.tabNumber}`]);
           }
       });
   }
   

Here is how it works: when our app receives the navigation command from the voice script, the navigateForward method is invoked to go to the tab having the number obtained from the user utterance.

You can test it: run the app, click the Alan button and say: Go to the second tab. The app will open the second tab. Then say: Go to the fifth tab. Alan will reply: The tab with this number is not found.

What’s next?

Have a look at the next tutorial: Passing the app state to the voice script (Ionic Angular).