title: <select> tag validates form with default value angular5
body: <p>I am working on angular5 template driven forms.</p>
  
  <p>Problem: I used select list in form, and provide the values array for select list from my demo.ts file. The  following are the options I provided:</p>
  
  <pre><code>this.states = []; 
  this.states.push( {label:'Select State', value:''}); 
  this.states.push( {label:'Maharashtra', value:'Maharashtra'}); 
  this.states.push( {label:'AndhraPradesh', value:'AndhraPradesh'}); 
  </code></pre>
  
  <p>My HTML code:</p>
  
  <pre><code>&lt;div class="ui-grid-col-4"&gt;
          &lt;p-dropdown [options]="states"  name="pass_state" [(ngModel)]="applicant.pass_state" [ngModelOptions]="{standalone: true}"
          [autoWidth]="false" #passstate="ngModel" required&gt;&lt;/p-dropdown&gt;
  
          &lt;div *ngIf="passstate.invalid &amp;&amp; (passstate.dirty || passstate.touched)" class="alert alert-danger"&gt;
            &lt;div [hidden]="!attempt.hasError('required')"&gt;state is mandatory&lt;/div&gt;
          &lt;/div&gt;
        &lt;/div&gt;
  </code></pre>
  
  <p>Question: I need to validate this form, but when I select default value form is getting submitted successfully with null values for states, I need to fill the mandatory sate.</p>