title: In Angular2, need sum of the value in text boxes
body: <p>In my Angular2 app, I have a <code>*ngFor</code> loop to show model names coming from JSON. 
  The parent template code looks like this</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div *ngFor="#model of datajson.models"&gt;
      &lt;models [data]="model"&gt;&lt;/models&gt;
  &lt;/div&gt;    
  </code></pre>
  
  <p>Now for the child component, the code looks like this</p>
  
  <pre class="lang-ts prettyprint-override"><code>@Component({
      selector: 'models',
      template: `
          {{data.modelname}}
          &lt;input type="text" class="txt-dev-number" [(ngModel)]="devCount"/&gt;
      `,
  </code></pre>
  
  <p>Here in the last line, I have a text box for each model name which will take numbers.
  Question is how to get the sum of all the values in the text boxes. </p>