面对angularjs验证中的问题

Question

  

单击“登录”按钮时，不显示错误消息。

<form name="loginform" ng-submit="loginform.$valid && login()" novalidate >
    <div class="form-group" ng-class="{ 'has-error' : loginform.username.$invalid && !loginform.username.$pristine }">
    <input type="email" name="username" class="form-control" ng-model="user.username" placeholder="Email" required>          
    <p ng-show="loginform.username.$touched && loginform.username.$invalid" class="help-block">The name is required.</p>
    <p ng-show="loginform.username.$touched && loginform.username.$error.email" class="help-block">Please enter valid email id.</p>
     </div>     
    <input type="password" ng-model="user.password" placeholder="Password" class="form-control">    <br>
    <button type="submit" value="Log in"  class="btn btn-primary" >Log In</button>
 </form>