registerBackButtonAction " page.isRootPage " is always undefined

Ionic Framework ionic-v3
1

registerBackButtonAction working bot not proper

don’t get " page && page.isRootPage "

page.isRootPage always undefined

mention below code in app.component.ts in ready section

     this.platform.registerBackButtonAction(() => {
        alert('Back button action called'); //called
        console.log("Back button action called");

        let activePortal =  this.ionicApp._loadingPortal.getActive() ||
           this.ionicApp._modalPortal.getActive() ||
            this.ionicApp._toastPortal.getActive() ||
            this.ionicApp._overlayPortal.getActive();
            alert('activePortal'+activePortal); // Result is : activePortalundefined
        if (activePortal) {
           ready = false;
           activePortal.dismiss();
           activePortal.onDidDismiss(() => { ready = true; });

           console.log("handled with portal");
           return;
        }

        if ( this.menu.isOpen()) {
            this.menu.close();
      alert('closing menu');
           console.log("closing menu");
           return;
        }

        let view = this.nav.getActive();
        alert('view'+view); // Result is : [object object]
        let page = view ? this.nav.getActive().instance : null;
        console.log('pages',page); // HomePage {navCtr: Nav, menu: MenuController, nav: undefined}
       
          console.log('pages',page); // result is in attachment 
        console.log('page.isRootPage',page.isRootPage);
        
         // alert(JSON.stringify(page)); // is comment out code is not working
          alert('page.isRootPage'+page.isRootPage); //// Result is : page.isRootPage undefined
         
        if (page && page.isRootPage) {
          alert('not root page');
           console.log("Handling back button on a home page");
           this.alertCtrl.create({
              title: 'Confirmation',
              message: 'Do you want to exit?',
              buttons: [
                 {
                    text: 'Cancel',
                    handler: () => {
                    }
                 },
                 {
                    text:'OK',
                    handler: () => {
                       this.platform.exitApp();
                    }
                 }
              ]
           }).present();
        }
        else if (this.nav.canGoBack() || view && view.isOverlay
        ) {
          alert('popping back')
           console.log("popping back");
           this.nav.pop();
        }
        else if (this.storage.get('hasLogin')
        ) {
          alert('Returning to home page') // Result is :Returning to home page (call last)
           console.log("Returning to home page");
           this.nav.setRoot(HomePage);
        }
        else if (!this.storage.get('hasLogin')) {
          alert('Not yet logged in... exiting')
           console.log("Not yet logged in... exiting");
            this.platform.exitApp();
        }
        else {
          //   alert('ERROR with back button handling')
           console.log("ERROR with back button handling");
        }

     }, 1);

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2

What is this.storage?

3

this.storage.get(‘hasLogin’) is store user login or not.
before login “hasLogin” is nothing after login it will store true value for check user already logdin.

4

That’s not what I asked. I asked what this.storage is. If it’s an instance of ionic-storage’s Storage, then get is returning Promises, and your code which is testing them for truthiness is not going to be doing what you seem to think it will.

2 Likes
5

okay cool,
you simply say page.isRootPage why undefined

and how to know i’m in root page or not?

6

use canGoBack() method of navController… It returns false when it is on root.