Form validation with NgModel angular 7

Question

I don't know how my Ngclass not working, if you found the solution thank you soo much

In my HTML :

<form [formGroup]="pageForm">
 ... 
 <input [(ngModel)]="namePage" type="text" class="form-control">
 ... 

<div class="d-flex mt-4">
  <i [ngClass]="{ 'is-valid': !f.name.errors }"></i>
</div>

</form>

In my TS:

pageForm: FormGroup;
namePage: string;

// the form
this.pageForm = new FormGroup({
  name: new FormControl([this.namePage, Validators.required]),
 });

get f() {
 return this.pageForm.controls;
}

Answer 1

Try

isValid: boolean = false;

get f() {
 this.isValid = this.pageForm.valid;
}

<form [formGroup]="pageForm"  (ngSubmit)="f()">
 ... 
 <input [(ngModel)]="namePage" type="text" class="form-control">
 ... 

<div class="d-flex mt-4">
  <i [ngClass]="{ 'is-valid': isValid }"></i>
</div>

</form>