Ionic 3 firebase display data error -

currently able post data firebase, can't data , display in ionic 3 app. shoes.ts file:

import { component } '@angular/core'; import { navcontroller, navparams } 'ionic-angular'; import { angularfiredatabase } "angularfire2/database"; import { firebaselistobservable } 'angularfire2/database'; @component({   selector: 'page-shoes',   templateurl: 'shoes.html', }) export class shoespage {   shoppingitems: firebaselistobservable<any[]>;   newitem = '';    getshoppingitems() {     return this.afdb.list('/shoppingitems/');   }   constructor(public navctrl: navcontroller, public navparams: navparams,  public afdb: angularfiredatabase){     this.additem("awesomestuff");     this.getshoppingitems();     alert(this.shoppingitems);   }    ionviewdidload() {     console.log('ionviewdidload shoespage');   }     additem(name) {     this.afdb.list('/shoppingitems/').push(name);   }    removeitem(id) {     this.afdb.list('/shoppingitems/').remove(id);   } } 

this part of shoes.html file:

 <ion-list>     <ion-item class="text" *ngfor="let item of shoppingitems | async">       {{item.$value}}     </ion-item>  </ion-list> 

any ideas how can able display firebase data? getting: [object object] when alert shoppinglist.