How to get rid of foreach error?

Question

Yii

I have such a problem in the main.php template, I have a problem and it displays the following entry Invalid argument supplied for foreach(). It's just not clear why foreach is disabled. Most likely, as I understand it, I use it in main. But how to implement the notification system then the question is. I've never done this myself and can't figure out how to do it.

<div class="wrap">
    <?php
    NavBar::begin([
        'brandLabel' => 'Holland',
        'brandUrl' => ['/zakaz/index'],
        'options' => [
            'class' => 'navbar-inverse navbar-fixed-top',
        ],
    ]);
    if (!Yii::$app->user->isGuest) {
        $menuItems[] = ['encode' => false, 'label' => '<span class="glyphicon glyphicon-bell"></span>', 'options' => ['id' => 'notification']];
    }
    if (Yii::$app->user->isGuest) {
        // $menuItems[] = ['label' => 'Signup', 'url' => ['/site/signup']];
        $menuItems[] = ['label' => 'Войти', 'url' => ['/site/login']];
    } else {
        $menuItems[] = '<li>'
            . Html::beginForm(['/site/logout'], 'post')
            . Html::submitButton(
                'Выйти (' . Yii::$app->user->identity->username . ')',
                ['class' => 'btn btn-link logout']
            )
            . Html::endForm()
            . '</li>';
    }
    echo Nav::widget([
        'options' => ['class' => 'navbar-nav navbar-right'],
        'items' => $menuItems,
    ]);
    NavBar::end();
    ?>
    <div class="notification-container">
                                                                                                                                                                   
        <?php foreach ($notification as $notifications): ?>
            <?php echo $notifications->name; ?>
        <?php endforeach ?>

        <?php Html::a('Прочитать все напоминание', ['#']) ?>
    </div>

Answer 1

In foreach you are passing the $notification variable, but where is its initialization? This variable must contain an array of objects. And it comes, apparently, null.