Ionic 4 Toggle ngModel does not work and checked handle does not exist

Bug Report

Ionic version:

[x] 4.x

Current behavior: My project uses ion-toggle and i set value checked of this tag by variable and some trigger. But when ionChange event run, i change value of variable by two-way binding, it not change in UI, i try with checked handle but the handle was off in #17012 In ionic framework docs, there are not any guide of this issue, can body have some solutions for my problem?

Related code:

in UI html

<ion-toggle [(ngModel)]="var1" mode="ios" 
        color="success" (ionChange)="change($event)">
</ion-toggle>

In ts first code

change(e){
       if(this.var1 == false && this.var2 == false){
              e.checked = true;
       }
}

In ts second code

change(e){
       if(this.var1 == false && this.var2 == false){
              this.var1 = true;
       }
}

Other information:

Ionic info:

Ionic:

   ionic (Ionic CLI)             : 4.10.3 (/usr/local/lib/node_modules/ionic)
   Ionic Framework               : @ionic/angular 4.1.1
   @angular-devkit/build-angular : 0.13.6
   @angular-devkit/schematics    : 7.2.4
   @angular/cli                  : 7.3.6
   @ionic/angular-toolkit        : 1.4.0

Cordova:

   cordova (Cordova CLI) : 8.1.2 (cordova-lib@8.1.1)
   Cordova Platforms     : none
   Cordova Plugins       : no whitelisted plugins (10 plugins total)

System:

   Android SDK Tools : 26.1.1 (/home/conganhpham/sdk-tools-linux-4333796)
   NodeJS            : v8.10.0 (/usr/bin/node)
   npm               : 6.8.0
   OS                : Linux 4.15

[saladgg]

@phamconganh , As of ionic 4, you access checked by adding .detail to the change method params; <ion-toggle [(ngModel)]=“var1” mode=“ios” color=“success” (ionChange)=“change($event.detail)”> </ion-toggle>

[liamdebeasi]

Hi there,

Thanks for the follow up. I was able to reproduce the issue. We will look into it!

As a temporary workaround, you can do:

setTimeout(() => {
  this.var1 = true;
  this.var2 = true;
  this.var3 = true;
  this.var4 = true;
 }, 0);

This approach should be removed when this bug gets fixed, but it should do the job for now.

Thanks for using Ionic!