if(!$model->create()){
    //如果错误,提示错误信息
    Yii::$app->session->setFlash('warming',$model->_lastError);
}else{
    return $this->redirect(['post/view','id'=>$model->id]);
}

出错的时候，这个异常信息在视图上不会显示

视图文件create.php

<?php
/**
 * Created by PhpStorm.
 * User: wjl
 * Date: 2018/8/16
 * Time: 16:31
 */
use yii\helpers\Html;
use yii\bootstrap\ActiveForm;

//添加标题
$this->title = '创建';
$this->params['breadcrumbs'][] =['label'=>'文章','url'=>['post/index']];//设置一个标签,并给定指向url
$this->params['breadcrumbs'][] = $this->title;

?>
<div class="row">
    <div class="col-lg-9">
        <div class="panel-title box-title">
            <span>创建文章</span>
        </div>

        <div class="panel-body">

         <?php $form=ActiveForm::begin()  ?>
         <!--yii的表单组件  yii可以直接使用$调用控制传过来的变量-->
         <?= $form->field($model, 'title')->textInput(['maxlength'=>true]) ?>
         <?= $form->field($model, 'cat_id')->dropDownList($cat) ?>
         <?= $form->field($model, 'label_img')->widget('common\widgets\file_upload\FileUpload',[
            'config'=>[
                //图片上传的一些配置，不写调用默认配置
            ]
          ]) ?>

            <?= $form->field($model, 'content')->widget('common\widgets\ueditor\Ueditor',[
                'options'=>[
                    'initialFrameWidth' => 850,
                    'initialFrameHeight' => 200,
                ]
            ]) ?>

            <?= $form->field($model, 'tags')->widget('common\widgets\tags\TagWidget') ?>
            <div class="form-group">
                <?= Html::submitButton('发布', ['class' => 'btn btn-primary']) ?>
            </div>

         <?php $form=ActiveForm::end()  ?>
        </div>
    </div>
    <div class="col-lg-3">
        <div class="panel-title box-title">
            <span>注意事项</span>
        </div>
        <div class="panel-body">
            1.asasa<br>
            2.asasa
        </div>
    </div>
</div>