AngularJS和Bootstrap3:表单验证和必需字段

我使用以下代码:

  <div class="m-grid-col-lg-10" 
       ng-class="{ 'has-error': nameForm.userName.$invalid }">
      <input type="text" name="userName" required ng-model="userName"
             class="form-control input-lg input-small" />
  </div>

<button class="btn btn-primary" type="button"
        ng-click="done(nameForm.$valid)">
    Done
</button>

 $scope.done = function (isValid) {
        if (isValid) {
            $modalInstance.close();
        }
        else {
            return false;
        }
    };

下面是一个jsiddle:

http://jsfiddle.net/aman1981/a0cLtnpr/7/