title: Angular dropdown validation
body: <p>I'm using Angular 5 with forms validator. I'm trying to validate a select dropdown to avoid send the form without the user select an item from the select. The problem is the validation is not working. The validator works fine for an input control but not for the dropdown.</p>
  
  <pre><code>&lt;div class="form-control"&gt;
      &lt;label class="form-control__label" for="accionReglas"&gt;País *&lt;/label&gt;
      &lt;p-dropdown formControlName="paisDropdown" class="dropdown" [options]="countriesOptions" [readonly]="this.isReadOnly || filtersForm.get('nacInterRadioButton').value === 'N'" filter="true" placeholder="Seleccione su país"  required="true"&gt;&lt;/p-dropdown&gt;
      &lt;div *ngIf="filtersForm.get('paisDropdown').errors &amp;&amp; (filtersForm.get('paisDropdown').dirty || filtersForm.get('paisDropdown').touched)"&gt;
          &lt;span *ngIf="filtersForm.get('paisDropdown').errors.required" class="form-control__msg-txt"&gt;El país es obligatorio.&lt;/span&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>TypeScript Code:</p>
  
  <pre><code>import { FormBuilder, FormGroup, FormControl, Validators, Validator } from '@angular/forms';
  
  this.filtersForm = this.fBuilder.group({
      "cifInput": new FormControl("", [ Validators.required, Validators.maxLength(10) ]),
      "paisDropdown": new FormControl([ Validators.required ])
  });
  </code></pre>
  
  <p>Thank you very much !!!</p>