Angular 6 Reactive Forms : How to set focus on first invalid input

Question

Under my Angular 6 app , i'm using Reactive Forms .

My purpose is when submitting , i want to set focus on first invalid input when error.

My form looks like this :

<form [formGroup]="addItemfForm " (ngSubmit)="onSubmitForm()">

  <div class="form-inline form-group">
    <label class="col-md-2 justify-content-start">
        Libellé du pef
        <span class="startRequired mr-1"> *</span>
    </label>
    <input type="text" maxlength="100" formControlName="libellePef" class="col-md-6 form-control" placeholder="saisie obligatoire" [ngClass]="{ 'is-invalid': submitted && formFiels.libellePef.errors }" />
    <div *ngIf="submitted && formFiels.libellePef.errors" class="col invalid-feedback">
      <div class="col text-left" *ngIf="formFiels.libellePef.errors.required">Libellé du pef est requis.</div>
    </div>
  </div>

  <div class="form-inline form-group">
    <label class="col-md-2 justify-content-start">
       Code Basicat
       <span class="startRequired mr-1"> *</span>
    </label>
    <input type="text" maxlength="100" formControlName="codeBasicat" class="col-md-3 form-control" placeholder="saisie obligatoire" [ngClass]="{ 'is-invalid': submitted && formFiels.codeBasicat.errors }" />
    <div *ngIf="submitted && formFiels.codeBasicat.errors" class="col invalid-feedback">
      <div class="text-left" *ngIf="formFiels.codeBasicat.errors.required">Code Basicat est requis.</div>
    </div>
  </div>

  <div class="form-inline form-group">
    <label class="col-md-2 justify-content-start">
        Nom de l'application
        <span class="startRequired mr-1"> *</span>
    </label>
    <input type="text" maxlength="100" formControlName="nomApplication" class="col-md-6 form-control" placeholder="saisie obligatoire" [ngClass]="{ 'is-invalid': submitted && formFiels.nomApplication.errors }" />
    <div *ngIf="submitted && formFiels.nomApplication.errors" class="col invalid-feedback">
      <div class="text-left" *ngIf="formFiels.nomApplication.errors.required">Nom de l'application est requis.
      </div>
    </div>
  </div>
</form>

Under my TS file , my form config looks like this :

this.addItemfForm = this.formBuilder.group({
  libellePef: ['', Validators.required],
  codeBasicat: ['', Validators.required ],
  nomApplication: ['', Validators.required ],
  urlCible: [''],
  modeTransfert: [''],
});

I've tried the autofocus directive but that didn't work

Suggestions?

Answer 1

Use below code in your submit.

for (const key of Object.keys(this.addressForm.controls)) {
      if (this.addressForm.controls[key].invalid) {
        const invalidControl = this.el.nativeElement.querySelector('[formcontrolname="' + key + '"]');
        invalidControl.focus();
        break;
     }
}

this.addressForm will be your FormGroup.

We don't even need directive here.

Answer 2

I did that using directives. So My form would look like this:

<form [formGroup]="userForm" (submit)="saveData()" appFocus >
...
</form>

and the code for the directive itself:

import { Directive, HostListener, Input, ElementRef } from '@angular/core';
import { NgForm } from '@angular/forms';

@Directive({
  selector: '[appFocus]'
})
export class FocusDirective {

  constructor(private el: ElementRef) { }

  @Input() formGroup: NgForm;

  @HostListener('submit', ['$event'])
  public onSubmit(event): void {
    if ('INVALID' === this.formGroup.status) {
      event.preventDefault();

      const formGroupInvalid = this.el.nativeElement.querySelectorAll('.ng-invalid');
      (<HTMLInputElement>formGroupInvalid[0]).focus();
    }
  }
}

However this solution is incomplete as there is a lot of corner cases that have to be considered. For example what if the first element is radio button group. Dispatching focus event will automatically mark the filed. Second not every element to which angular ads ng-invalid will be an input.