Cannot read property 'navCtrl' of null ionic3

Question

The problem is that I wanna make an event in alert(button) that I wanna make it move me to another page and this button no longer exist in HTML that the reason I can't make a (click) function and when I run it, give me no provider error "No provider for NavController". I tried another option

I used ViewChild and import it from @angular/core,
make @viewChild('myApp') and added this #myApp to ion-nav
define navCtrl: NavController in class.

In a constructor, I added public push: Push but it can't read it. in this time it gives me "Cannot read property 'navCtrl' of null".

import { Component }                                       from '@angular/core';
import { Platform, Alert, AlertController, NavController } from 'ionic-angular';
import { StatusBar }                                       from '@ionic-native/status-bar';
import { SplashScreen }                                    from '@ionic-native/splash-screen';
import   firebase                                          from 'firebase';
import { FirebaseProvider }                                from '../providers/firebase/firebase';
import { ViewProvider }                                    from '../providers/view/view';

//pages
import { OpenPage } from '../pages/open/open';
import { AcceptOrderPage } from '../pages/accept-order/accept-order';

@Component({
  templateUrl: 'app.html'
})

 export class MyApp {
  rootPage = OpenPage;
  public marginClass:any="normal";
  public available:boolean=true;
  public orderId:string;
  public alert: Alert;

  constructor(platform: Platform, statusBar: StatusBar, splashScreen:
   SplashScreen, public fb: FirebaseProvider,
   public view: ViewProvider, private alertCtrl: AlertController, public 
   navCtrl: NavController) {
    platform.ready().then(() => {
     if (platform.is('ios')){
      this.marginClass="iosMargin"
     }
   statusBar.styleDefault();
   splashScreen.hide();
  });
    var config = {
      apiKey: "AIzaSyDbn0bLyNh4emJXjVAKb_BsOyH7ahiY-3U",
      authDomain: "cat-drivers.firebaseapp.com",
      databaseURL: "https://cat-drivers.firebaseio.com",
      projectId: "cat-drivers",
      storageBucket: "cat-drivers.appspot.com",
      messagingSenderId: "444330551162"
    };
    firebase.initializeApp(config);

    var starCountRef = 
     firebase.database().ref('drivers/'+this.orderId+'/Orders');
     starCountRef.on('value', function(snapshot) {
       let alert = alertCtrl.create({
         title: 'لديك طلب جديد؟',
          buttons: [
         {
          text: 'رفض',
          role: 'cancel',
          handler: () => {
            console.log('Cancel clicked');
          }
         },
         {
          text: 'قبول',
          handler: () => {
            console.log('Buy clicked');
            navCtrl.push(AcceptOrderPage);
          }
         }
       ]
     });
     alert.present();
  });
 }
    sendData(x){
      this.view.localGet("uid").then((uid)=>{
      this.fb.setData('drivers/'+uid+'/outOfService/',x)})
    }

    toggleState(item){
     this.available=!this.available;
      // console.log(this.available)
     } 
  }

amin arghavani amin arghavani · Accepted Answer · 2017-09-27T19:16:41

Please check this code:

var starCountRef = 
 firebase.database().ref('drivers/'+this.orderId+'/Orders');
var _that=this;
 starCountRef.on('value', function(snapshot) {
   let alert = alertCtrl.create({
     title: 'لديك طلب جديد؟',
      buttons: [
     {
      text: 'رفض',
      role: 'cancel',
      handler: () => {
        console.log('Cancel clicked');
      }
     },
     {
      text: 'قبول',
      handler: () => {
        console.log('Buy clicked');
        _that.navCtrl.push(AcceptOrderPage);
      }
     }
   ]
 });
 alert.present();

Cannot read property 'navCtrl' of null ionic3

1 Answers