I have used reactive forms in my angular 2 project. I'm trying to do button validation but facing bit confuse. Here my form contains several text fields and buttons. In my form there are two way's to give input. i.e through input textfields and upload spread sheet button.

If we try to give input from text fields, my upload button should disable and If remove data from textfields upload button should enable. How to achieve this functionality.

Sample example: <https://stackblitz.com/edit/angular-vnqqcx>