Issue with change detection in ionic 3 app

Question

Data is changing in service and component but it's not getting reflected on view.

Following are the solutions used which didn't solve the issue :

Used lifecycle hook ngDoCheck
Used angular zone and called method inside zone.run()
Invoked change detection manually by calling ChangeDetectorRef.detectChanges()
Added timer of 5 sec before calling the methods.

My code:

ngOnInit() {
this.noticeService.notices.subscribe(data => {
  this.notices = data;
});
}

The issue is whenever I debug the code I found that data is reflected in notices variable of component but its not getting displayed on UI unless any user action like click is not performed. Your help is much appreciated.

Kindly provide complete code. – Syed Kashan Ali Aug 20 '18 at 08:34 — Syed Kashan Ali, Aug 20 '18 at 08:34

score 3 · Answer 1 · answered Aug 20 '18 at 08:35

3

I have solved the issue just by moving my subscription code from ngOnInit() to constructor(). I don't know why it works only in constructor and also not found any relevant information regarding it. I also found that someone has already faced the same issue.

Why observable.subscribe works only from constructor

answered Aug 20 '18 at 08:35

Shrutika Patil

565
3
18

It might be possible, you forgot to add 'implements OnInit' next to the component name and thats why this method was not calling from your code. – Mangesh Daundkar Aug 20 '18 at 11:03
@MDM I have implemented OnInit() – Shrutika Patil Aug 20 '18 at 12:26

Issue with change detection in ionic 3 app

1 Answers1