PHP设置函数内的变量'；s函数

我需要关于设置变量的建议。我正在使用Slim框架。我很少上课

MailboxManager.php

    public function getMailById($id) {
        /* @var $sql PDOStatement */
        $sql = $this->database->prepare("SELECT * FROM appmail_mails WHERE id = :id");
    $sql->bindParam('id', $id);
    $sql->execute();
    $record = $sql->fetch(PDO::FETCH_ASSOC);
    if ($record === false) {
        return null;
    }
    $mail = new Mail($id);
    $mail->setMailContent($record['content']);
    $mail->setMailDate($record['date']);
    $mail->setMailSubject($record['subject']);
    $mail->setMailSize($record['
return $mail;

class MailController
private $id;
public function showMail()
    $mail = ServicesFactory::getMailboxManager()->getMailById($this->id);
    echo "<pre>";
    var_dump($mail);

MailController.php

    public function getMailById($id) {
        /* @var $sql PDOStatement */
        $sql = $this->database->prepare("SELECT * FROM appmail_mails WHERE id = :id");
    $sql->bindParam('id', $id);
    $sql->execute();
    $record = $sql->fetch(PDO::FETCH_ASSOC);
    if ($record === false) {
        return null;
    }
    $mail = new Mail($id);
    $mail->setMailContent($record['content']);
    $mail->setMailDate($record['date']);
    $mail->setMailSubject($record['subject']);
    $mail->setMailSize($record['
return $mail;

class MailController
private $id;
public function showMail()
    $mail = ServicesFactory::getMailboxManager()->getMailById($this->id);
    echo "<pre>";
    var_dump($mail);

我应该如何设置以下项的id：

$test = $new->showMail($id)

为了得到它？ 每次我试图：

$app->get('/dupa/{id}', function(ServerRequestInterface $request, $response, $args){

    $id = $args['id'];
    echo $id;
    $new = new MailController();
    $test = $new->showMail();
    var_dump($test);
});

我只是得到空值

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谢谢您的帮助。

路由参数作为第三个参数传递给闭包

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您的

showMail（）

确实返回任何内容？？是的，它返回null您的函数

showMail（）

不需要任何id。您希望MailController如何获取id？