AngularJS验证传递所需的空字段

Question

表单部分的视图看起来像

<md-dialog aria-label="Add Attendee">
  <form ng-cloak class="form-horizontal" name="attendeeForm" ng-submit="save(ctrl.attendee) && attendeeForm.$valid" novalidate>
    <md-toolbar>
      <div class="md-toolbar-tools">
        <h2>Enter Attendee</h2>
        <span flex></span>
        <md-button class="md-icon-button" ng-click="cancel()">
          <md-icon md-svg-src="img/icons/ic_close_24px.svg" aria-label="Close dialog"></md-icon>
        </md-button>
      </div>
    </md-toolbar>

    <md-dialog-content>
      <div class="md-dialog-content">
        <div class="form-group">
          <label for="firstName" class="control-label col-md-3 col-sm-4">First Name:</label>
          <div class="col-sm-8"><input type="text" class="form-control" id="firstName" placeholder="First Name" name="firstName" ng-model="ctrl.attendee.firstName" ng-required="true" /></div>
        </div>
        <div class="form-group">
          <label for="lastName" class="control-label col-md-3 col-sm-4">Last Name:</label>
          <div class="col-sm-8"><input type="text" class="form-control" id="lastName" placeholder="Last Name" name="lastName" ng-model="ctrl.attendee.lastName" ng-required="true" /></div>
        </div>
        <div class="form-group">
          <label for="email" class="control-label col-md-3 col-sm-4">Email:</label>
          <div class="col-sm-8"><input type="email" class="form-control" id="email" placeholder="Email Address" name="email" ng-model="ctrl.attendee.email" ng-required="true" /></div>
        </div>
      </div>
    </md-dialog-content>

    <md-dialog-actions layout="row">
      <span flex></span>
      <button class="btn btn-primary" type="submit">Save Attendee</button>
    </md-dialog-actions>
  </form>
</md-dialog>

当我提交没有必填字段的表单时，表单会通过验证并可以提交。当我删除novalidate时，根据来自Angularjs prevent form submission when input validation fails的回答没有任何意义，其中表示不需要控制器检查。

有什么想法吗？