Php 未定义的属性-Symfony2

我用的是Symfony2。我的控制器找到一些由创建的值（如类别），并将它们提供给模板。问题是，如果用户还没有创建任何类别，我想显示一个消息，邀请他创建类别

代码如下：

    if($number_of_categories == 0){
        $newcommer = true;

        //Here the template doesn't need any variables, because it only displays
        // "Please first add some categories"
    } else {
        $newcommer = false;

        //Here the variables, which I give to the template 
        //are filled with meaningfull values
    }

return $this->render('AcmeBudgetTrackerBundle:Home:index.html.twig', array(
        'newcommer' => $newcommer,
        'expenses' => $expenses_for_current_month,
        'first_category' => $first_category,
        'sum_for_current_month' => $sum_for_current_month,
        'budget_for_current_month' => $budget_for_current_month
));

问题是，如果用户没有类别，我就没有填充变量的内容，所以我必须这样写：

        //What I want to avoid is this: 
        $expenses_for_current_month = null;
        $first_category = null;
        $sum_for_current_month = null;
        $budget_for_current_month = null;

只是为了避免

注意：未定义变量…

是否有更清洁的解决方案来实现这一点？没有一种方法可以动态生成给定给模板的变量计数，是吗？提前谢谢

这里有一个简单的解决方案（如果我理解你的问题）：

如果您想要一个更干净的解决方案来管理模板，您可以使用注释（您只需返回一个数组来传递给视图）：

---

我认为有很多方法可以满足你的需求，但首先，你需要更准确地告诉我们。无论是否有类别，都可以渲染“衍射”模板。也许你可以在你的小枝模板中签入$newcommer的值，然后显示你想要的。更具体地说你的目标是什么谢谢你！我还没想到呢！

$template = 'AcmeBudgetTrackerBundle:Home:index.html.twig';

if ($number_of_categories == 0){

    //Here the template doesn't need any variables, because it only displays
    // "Please first add some categories"

    return $this->render($template, array(
        'newcommer' => true,
    ));

} else {

    //Here the variables, which I give to the template 
    //are filled with meaningfull values

    return $this->render($template, array(
        'newcommer' => false,
        'expenses' => $expenses_for_current_month,
        'first_category' => $first_category,
        'sum_for_current_month' => $sum_for_current_month,
        'budget_for_current_month' => $budget_for_current_month
    ));
}

// ...

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Template;

class MyController extends Controller
{
    /**
     * @Route("/my_route.html")
     * @Template("AcmeBudgetTrackerBundle:Home:index.html.twig")
     */
    public function indexAction()
    {
            // ...

        if ($number_of_categories == 0){

            return array(
                'newcommer' => true,
            );

        } else {

            //Here the variables, which I give to the template 
            //are filled with meaningfull values

            return array(
                'newcommer' => false,
                'expenses' => $expenses_for_current_month,
                'first_category' => $first_category,
                'sum_for_current_month' => $sum_for_current_month,
                'budget_for_current_month' => $budget_for_current_month
            );
        }
    }
}