title: How to prevent ion-checkbox from selecting the same item value?
body: <p>This is an accordion list menu and at the 3rd level of the menu, I put a checkbox for each item. This code already getting the value from the item selected but the problem is when I cancel my selection it keeps me getting its value. How can I prevent a checkbox from selecting the same item and cancel if it is selected?</p>
  
  <p>form.html</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;!-- Third-Level --&gt;
  &lt;ion-item *ngFor="let item of child.children" detail-none class="child-item" 
            text-wrap no-lines&gt;
     &lt;ion-label&gt;
        {{ item.name }} 
        &lt;p style="color: #0077ff;"&gt;
           {{ item.open ? 'Item Selected' : '' }}
        &lt;/p&gt; 
     &lt;/ion-label&gt;
     &lt;!-- &lt;ion-checkbox item-end (click)="tofix(item)"&gt;&lt;/ion-checkbox&gt; --&gt;
     &lt;ion-checkbox item-end [(ngModel)]="item.open" (click)="tofix(item)"&gt;&lt;/ion-checkbox&gt;
  &lt;/ion-item&gt;
  </code></pre>
  
  <p>form.ts</p>
  
  <pre class="lang-js prettyprint-override"><code>export class FormPage  implements OnInit{
     data: any[];
  
     @Input('item') item: any;
  
     constructor(
        public navCtrl: NavController, 
        public navParams: NavParams, 
        private http: Http,
        private toastCtrl: ToastController) {
           this.http.get('assets/data/menus.json')
              .map(res =&gt; res.json().items)
              .subscribe(data =&gt; this.data = data);
  
           this.title = navParams.get('title');
           this.subtitle = navParams.get('subtitle');
      }
  
     toggleSection(i) {
        this.data[i].open = !this.data[i].open;
     }
  
     toggleItem(i, j) {
        this.data[i].children[j].open = !this.data[i].children[j].open;
     }
  
     ngOnInit() {
     }
  
     async tofix(item){
        const toast = await this.toastCtrl.create({
           message: `Added item to be fix : ${item.name}`,
           duration: 2000
        }); 
  
        this.SelectedItemToFix += `${item.name}`;
        toast.present();
     }
  
     ionViewDidLoad() {
        console.log('ionViewDidLoad FormPage');
     }   
  }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/eMNBP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eMNBP.png" alt="Select"></a><a href="https://i.stack.imgur.com/KE4Xv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KE4Xv.png" alt="Cancel Select"></a></p>