Ich bin sehr neu in Typescript und Ionic 2 und versuche, mit der Ionic 2-Suchleiste durch eine Json-Antwort zu filtern.

Dies ist mein Code:

import {Component} from '@angular/core';
import {NavController} from 'ionic-angular';
import {Http} from '@angular/http';
import 'rxjs/add/operator/map';



@Component({
  templateUrl: 'build/pages/home/home.html'
})
export class HomePage {

  posts: any;
  private searchQuery: string = '';
  private items: string[];
  constructor(private http: Http) {

    this.initializeItems();

    this.http.get('https://domain.co/open.jsonp').map(res => res.json()).subscribe(data => {
        this.posts = data;
        console.log(this.posts);

    });

  }

  initializeItems() {
    this.items = this.posts;
  }

  getItems(ev: any) {
    // Reset items back to all of the items
    this.initializeItems();

    // set val to the value of the searchbar
    let val = ev.target.value;

    // if the value is an empty string don't filter the items
    if (val && val.trim() != '') {
      this.items = this.items.filter((item) => {
        return (item.toLowerCase().indexOf(val.toLowerCase()) > -1);
      })
    }
  }

}

Und das Markup:

<ion-header>
  <ion-searchbar (ionInput)="getItems($event)" [debounce]="500" placeholder="Suchen..."></ion-searchbar>
</ion-header>

<ion-content>
  <ion-list>
    <ion-item *ngFor="let post of posts">
      <h1>{{post.storeName}}</h1>
    </ion-item>
  </ion-list>
</ion-content>

Ich diesen Fehler, wenn ich suche:

item.toLowerCase ist keine Funktion

Die JSON-Daten sehen folgendermaßen aus:

[
{
storeName: "Avec Hauptbahnhof",
addressLink: "",
phone: "0326223902",
image: "",
description: "",
link: "",
openingHours: [
"05.30 - 22:00",
"05.30 - 22:00",
"05.30 - 22:00",
"05.30 - 22:00",
"05.30 - 22:00",
"06.30 - 22:00",
"7.00 - 22.00"
]
},
{
storeName: "Manor",
addressLink: "",
phone: "0326258699",
image: "",
customer: "",
description: "",
link: "",
openingHours: [
"09.00 - 18.30",
"09.00 - 18.30",
"09.00 - 18.30",
"09.00 - 21:00",
"09.00 - 18.30",
"08.00 - 17.00",
"Geschlossen"
]
}
]