PHP数组到字符串的转换问题

我想显示所有数据从$result在我的表，但有一些错误。
注意事项是"数组到字符串的转换"
这里是控制器:

public function actionIndex()
  {
      $command = Yii::app()->db->createCommand('
        Select username as user
        From application_admin aa, application a
        Where a.app_id = aa.app_id');
        $reader = $command->query();
        $dataUser = $reader->readAll();
    $dataProvider = Application::model()->findAll();
    foreach ($dataProvider as $data) {
      $temp = array();
              $name = $data->name;
              $customer = $dataUser;
              $category = $data->appCategory->name;
              $temp['name'] = $name;
              $temp['customer'] = $customer;
              $temp['category'] = $category;
              $result[] = $temp;
    }
    $this->render('index',array('result'=>$result));
  }  

，这是视图:

<?php
    $i=1;
        foreach ($result as $data){
  ?>
        <tr class="center clickableRow">
            <div>
                <td><?php echo $i; ?></td>
                <td><?php echo $data['name']; ?></td>
                <td><?php echo $data['customer'];?></td>   //error in this line
                <td><?php echo $data['category'];?></td>
            </div>
        </tr >
        <?php
            $i++;
        }
  ?>   

请给我一些建议，谢谢