未定義的屬性-Symfony2

Question

我正在使用Symfony2。 我的控制器會找到一些值，例如由創建的類別，並將其提供給模板。 問題是，如果用戶尚未創建任何類別，我想顯示一條消息邀請他創建類別。

這是代碼：

    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
));

問題是，如果用戶沒有類別，我就沒有什么填充變量，因此我必須編寫如下內容：

        //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;

只是為了避免Notice: Undefined variable ...

有沒有更清潔的解決方案來實現這一目標？ 沒有一種方法可以動態生成分配給模板的變量計數，是否存在？ 提前致謝！

Answer 1

這里是一個簡單的解決方案（如果我理解您的問題）：

$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
    ));
}

而且，如果您想使用更清潔的解決方案來管理您的模板，可以使用注釋@Template（） （只需返回一個數組即可傳遞到視圖）：

// ...

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
            );
        }
    }
}