angular custom validation
<p>
<label for="full_name">Full Name</label>
<!-- each form must have name and html validation -->
<!-- must have ng-class variable object with classes like this -->
<input type="text" ng-model="formModel.fullname" name="full_name" required="required"
ng-pattern="^[a-zA-Z][a-zA-Z0-9-_\.]{1,20}$"
ng-class="{
green: theForm.full_name.$valid ,
red: !theForm.full_name.$valid && !theForm.$pristine
}"
>
</p>