title: Radio button validation is not working in angular 7
body: <p>Radio button validation is not working in angular 7. i am using template driven approach. firstname, lastname and department validation are working as expected. </p>
  
  <p>I have followed same approach which i have done for text field</p>
  
  <p>register-component.html</p>
  
  <pre><code> &lt;form class="form" #e="ngForm" (ngSubmit)="empRegistrationData(e)" &gt;
   &lt;div class="form-group"&gt;
    &lt;label for="firstName"&gt; First Name &lt;/label&gt;
    &lt;input type="text" class="form-control" id="firstName" required 
        [(ngModel)]="empData.firstName" #firstName="ngModel" 
      name="firstName" [ngClass]="{'is-invalid': e.submitted &amp;&amp; 
         firstName.invalid}"/&gt;
            &lt;div *ngIf="e.submitted &amp;&amp; firstName.invalid" class="invalid- 
            feedback"&gt;
      &lt;div *ngIf="firstName.errors.required"&gt;First Name is mandatory&lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  
   &lt;div class="form-group"&gt;
    &lt;label&gt; Gender &lt;/label&gt; &lt;br /&gt; 
    &lt;div class="form-check-inline"&gt;
      &lt;label class="form-check-label"&gt;
        &lt;input type="radio" class="form-check-input" required name="gender" [(ngModel)]="empData.gender" #gender="ngModel" value="Male" &gt;Male
      &lt;/label&gt;
    &lt;/div&gt;
    &lt;div class="form-check-inline"&gt;
      &lt;label class="form-check-label"&gt;
        &lt;input type="radio" class="form-check-input" name="gender" [(ngModel)]="empData.gender" #gender="ngModel" value="Female" required&gt;Female
      &lt;/label&gt;
    &lt;/div&gt;
    &lt;div *ngIf="e.submitted &amp;&amp; gender.invalid" class="invalid-feedback"&gt;
        &lt;div *ngIf="gender.errors.required"&gt;Gender is mandatory&lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  &lt;div class="form-group"&gt;
    &lt;button type="submit" class="btn btn-primary mr-md-3"&gt;Register&lt;/button&gt;
    &lt;button type="button" class="btn btn-danger" 
       (click)="clearValues()"&gt;Clear&lt;/button&gt;
  &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>when i click on submit error message should display for radio button but error message is not displaying.</p>