Set invalid invalid form control in angular2

Question

Is it possible to set invalid form control in angular2? (used form builder)

eg. I have form-> exampleFrom and field-> exampleControl

I tried this, it failed:

this.exampleFrom.controls['exampleControl'].invalid 

Answer 1

Try

let control = this.exampleFrom.controls['exampleControl'];
control.setErrors({backend: {someProp: "Backend message"}});
let message = control.errors['backend'].someProp;

Answer 2

try this code to print a message

 <div style='color:red' *ngIf="!exampleFrom.exampleControl.valid">
                        //set here your custom message
          </div>