title: How to add a property to NgForm values
body: <p>I currently have an Angular form that returns the form values using (ngSubmit). I want to add another property to, lets say an input, where I can specify a search operator like (contains, equal, starts with, etc). </p>
  
  <p>How can I get the operator with the values from the form?</p>
  
  <p>Here's an example. I added <code>operator</code> to both inputs. I'd like to return this in the form value when search is called. Is there a custom directive I could write or a way to extend form values?</p>
  
  <pre><code>&lt;form #searchForm="ngForm" (ngSubmit)="search(searchForm)"&gt;
      &lt;input type="text" name="name" [(ngModel)]="name" operator="contains" /&gt;
      &lt;input type="text" name="email" [(ngModel)]="email" operator="equal" /&gt;
  &lt;/form&gt;
  
  search(form: NgForm) {
      console.log(form.value);
  }
  </code></pre>
  
  <p>So I would get something like this back or be able to bind to that operator.</p>
  
  <pre><code>name: { value: 'John', operator: 'contains' }
  </code></pre>