Event for changing Ionic 2 page

Question

Event for changing Ionic 2 page

Is there a way to execute code every time the page changes without adding an ngOnDestroy method to every page in Ionic 2?

Instead of using Ionic 2 page lifecycle hooks like ionViewDidUnload, is there a simpler solution by adding a single method to the main app class for the same effect?

I've noticed that Angular 2 Router events can be subscribed to, but how can this be translated for use in Ionic 2? I encountered an error when trying to import

{ Router } from '@angular/router;

.

TypeScript error: <path>/node_modules/@angular/router/src/common_router_providers.d.ts(9,55): Error TS2305: Module '"<path>/node_modules/@angular/core/index"' has no exported member 'NgModuleFactoryLoader'.
TypeScript error: <path>/node_modules/@angular/router/src/router.d.ts(14,39): Error TS2305: Module '"<path>/node_modules/@angular/core/index"' has no exported member 'NgModuleFactoryLoader'.
TypeScript error: <path>/node_modules/@angular/router/src/router_module.d.ts(9,10): Error TS2305: Module '"<path>/node_modules/@angular/core/index"' has no exported member 'ModuleWithProviders'.

Can the Nav or NavController service from ionic-angular be used instead for this purpose?

angular typescript ionic-framework ionic2 ionic3

Answer 1

Answer №1

Ionic2 has its own implementation of navigation with the NavController, rather than using Angular2's Router.

If you are familiar with subscribing to Angular 2 Router events, you can achieve similar functionality in Ionic 2.

To subscribe to navigation events in Ionic 2, you can merge all the NavController Events.

allEvents = Observable.merge(
                 this.navController.viewDidLoad, 
                 this.navController.viewWillEnter, 
                 this.navController.viewDidEnter, 
                 this.navController.viewWillLeave, 
                 this.navController.viewDidLeave, 
                 this.navController.viewWillUnload);

allEvents.subscribe((e) => {
    console.log(e);
});

Answer 2

Ionic2 has its own implementation of navigation with the NavController, rather than using Angular2's Router.

If you are familiar with subscribing to Angular 2 Router events, you can achieve similar functionality in Ionic 2.

To subscribe to navigation events in Ionic 2, you can merge all the NavController Events.

allEvents = Observable.merge(
                 this.navController.viewDidLoad, 
                 this.navController.viewWillEnter, 
                 this.navController.viewDidEnter, 
                 this.navController.viewWillLeave, 
                 this.navController.viewDidLeave, 
                 this.navController.viewWillUnload);

allEvents.subscribe((e) => {
    console.log(e);
});

Answer 3

Answer №2

If you want to streamline your code, consider creating a superclass that utilizes the ionViewDidUnload method (or any other lifecycle hook) in the following way:

import { Events } from 'ionic-angular';

export class BasePage {

  constructor(public eventsCtrl: Events) { }

  ionViewDidEnter() {
    this.eventsCtrl.publish('page:load');   
  }

  ionViewDidUnload() {
    this.eventsCtrl.publish('page:unload');   
  }
}

Then, simply extend the BasePage in every page:

@Component({
  templateUrl: 'build/pages/my-page/my-page.html',
})
export class MyPage extends BasePage {

constructor(private platform: Platform,
              private nav: NavController, 
              private menuCtrl: MenuController,
              ...,
              eventsCtrl: Events)
  {    

    super(eventsCtrl);

    //...
}

In your main app.ts file, add a method like the one below to handle these events:

private initializeEventHandlers() {

    this.events.subscribe('page:load', () => {
      // your code...
    });

    this.events.subscribe('page:unload', () => {
      // your code...
    });

  }

Answer 4

If you want to streamline your code, consider creating a superclass that utilizes the ionViewDidUnload method (or any other lifecycle hook) in the following way:

import { Events } from 'ionic-angular';

export class BasePage {

  constructor(public eventsCtrl: Events) { }

  ionViewDidEnter() {
    this.eventsCtrl.publish('page:load');   
  }

  ionViewDidUnload() {
    this.eventsCtrl.publish('page:unload');   
  }
}

Then, simply extend the BasePage in every page:

@Component({
  templateUrl: 'build/pages/my-page/my-page.html',
})
export class MyPage extends BasePage {

constructor(private platform: Platform,
              private nav: NavController, 
              private menuCtrl: MenuController,
              ...,
              eventsCtrl: Events)
  {    

    super(eventsCtrl);

    //...
}

In your main app.ts file, add a method like the one below to handle these events:

private initializeEventHandlers() {

    this.events.subscribe('page:load', () => {
      // your code...
    });

    this.events.subscribe('page:unload', () => {
      // your code...
    });

  }

Answer 5

Answer №3

With the release of Ionic 3.6, a new feature allows you to subscribe to application-wide page change events using the App component. Detailed documentation can be found at: https://ionicframework.com/docs/api/components/app/App/

For instance, if you want to monitor all view changes in Google Analytics through the GA Cordova plugin, you can modify your app.component.ts as follows:

constructor(private app: App, private platform: Platform, private ga: GoogleAnalytics, ...) {
  this.platform.ready().then(() => {
    this.ga.startTrackerWithId('UA-XXX').then(() => {
      this.app.viewDidEnter.subscribe((evt) => {
        // evt.instance is the Ionic page component
        this.ga.trackView(evt.instance.title);
      });
    }).catch(e => console.log('Oops', e));
  }
}

Answer 6

With the release of Ionic 3.6, a new feature allows you to subscribe to application-wide page change events using the App component. Detailed documentation can be found at: https://ionicframework.com/docs/api/components/app/App/

For instance, if you want to monitor all view changes in Google Analytics through the GA Cordova plugin, you can modify your app.component.ts as follows:

constructor(private app: App, private platform: Platform, private ga: GoogleAnalytics, ...) {
  this.platform.ready().then(() => {
    this.ga.startTrackerWithId('UA-XXX').then(() => {
      this.app.viewDidEnter.subscribe((evt) => {
        // evt.instance is the Ionic page component
        this.ga.trackView(evt.instance.title);
      });
    }).catch(e => console.log('Oops', e));
  }
}

Answer 7

Answer №4

The first thing to note is that the Router can be found in the @angular/router module.

To listen for route change events, you can subscribe to the router's changes object.

Sample Code

class MyRouteEventClass {
  constructor(private router: Router) {
     router.changes.subscribe((val) => {
       /* Add your awesome code here */
     }
    )
  }
}

Answer 8

The first thing to note is that the Router can be found in the @angular/router module.

To listen for route change events, you can subscribe to the router's changes object.

Sample Code

class MyRouteEventClass {
  constructor(private router: Router) {
     router.changes.subscribe((val) => {
       /* Add your awesome code here */
     }
    )
  }
}

Answer 9

Answer №5

If you're using Ionic2-RC0, you have the option to utilize plain old Javascript within app.component.ts. Here's an example:

import { Component } from '@angular/core';
import { Platform } from 'ionic-angular';
import { StatusBar } from 'ionic-native';

import { YourPage } from '../pages/yourpage/yourpage';

@Component({
  template: `<ion-nav [root]="rootPage"></ion-nav>`
})
export class MyApp {
  rootPage = YourPage;

  constructor(platform: Platform) {
    platform.ready().then(() => {

      // Once the platform is ready and plugins are accessible, you can perform any necessary native operations.
      StatusBar.styleDefault();
      window.addEventListener('load', () =>{
         console.log('page changed');
      });
    });
  }

Whenever you navigate to a different page using the NavController, the message page changed will be displayed in the console.

Answer 10

If you're using Ionic2-RC0, you have the option to utilize plain old Javascript within app.component.ts. Here's an example:

import { Component } from '@angular/core';
import { Platform } from 'ionic-angular';
import { StatusBar } from 'ionic-native';

import { YourPage } from '../pages/yourpage/yourpage';

@Component({
  template: `<ion-nav [root]="rootPage"></ion-nav>`
})
export class MyApp {
  rootPage = YourPage;

  constructor(platform: Platform) {
    platform.ready().then(() => {

      // Once the platform is ready and plugins are accessible, you can perform any necessary native operations.
      StatusBar.styleDefault();
      window.addEventListener('load', () =>{
         console.log('page changed');
      });
    });
  }

Whenever you navigate to a different page using the NavController, the message page changed will be displayed in the console.

Answer 11

Answer №6

If you're using Ionic2 or later, you can easily listen for specific events to trigger your code like this:

this.navCtrl.ionViewWillUnload.subscribe(view => {
    console.log(view);
});

Check out the Lifecycle Events documentation to subscribe to all available events.

Answer 12

If you're using Ionic2 or later, you can easily listen for specific events to trigger your code like this:

this.navCtrl.ionViewWillUnload.subscribe(view => {
    console.log(view);
});

Check out the Lifecycle Events documentation to subscribe to all available events.

Event for changing Ionic 2 page

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

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