How to discard changes and reload object when go back nav?

Indeed. Thanks aoathout.
That is what I need I think. I was not aware of this.

https://ionicframework.com/docs/v2/resources/forms/

https://forum.ionicframework.com/t/how-to-validate-forms-with-angular-2-in-ionic-2/54687/3

http://www.joshmorony.com/advanced-forms-validation-in-ionic-2/

Ok, I will try one of these methods.
Thanks for the information.