form validation in AngularJS

<form name="myForm">
    <label>
       User name:
       <input type="text" name="userName" ng-model="user.name" required>
    </label>
      <span class="error" ng-show="myForm.userName.$error.required"> Required!</span>
    <label>
       Last name:
       <input type="text" name="lastName" ng-model="user.last" ng-minlength="3" ng-maxlength="10">
    </label>
      <span class="error" ng-show="myForm.lastName.$error.minlength">Too short!</span>
      <span class="error" ng-show="myForm.lastName.$error.maxlength">Too long!</span>
 </form>