Edit in Plunker
<form name="myForm">
  <label>Enter your name:</label>
  <input type="text"
         name="myName"
         ng-model="name"
         ng-minlength="5"
         ng-maxlength="20"
         required />

  <pre>myForm.myName.$error = {{ myForm.myName.$error | json }}</pre>

  <div ng-messages="myForm.myName.$error" style="color:maroon">
    <div ng-message="required">You did not enter a field</div>
    <div ng-message="minlength">Your field is too short</div>
    <div ng-message="maxlength">Your field is too long</div>
  </div>
</form>
angular.module('ngMessagesExample', ['ngMessages']);