如何使用angularjs实现对表单元素的脏检查

Question

我想对表单中的所有必需元素实施脏检查

我试过这样的

<div ng-app="">
  <form name="myForm" ng-controller="Ctrl">
    <label>
        userType:
    </label> 
    <input name="usertype" ng-model="userType" required>
    <span class="error" ng-show="myForm.userType.$dirty">Required</span><br> 
    <label>
        designation:
    </label> 
    <input name="designation" ng-model="Designation" required>
    <span class="error" ng-show="myForm.Designation.$dirty">Required</span><br>    
   </form>
</div>