formwork/panel/views/fields/page.php

<?php $this->layout('fields.field') ?>
<select <?= $this->attr([
            'class'    => 'form-select',
            'id'       => $field->name(),
            'name'     => $field->formName(),
            'required' => $field->isRequired(),
            'disabled' => $field->isDisabled(),
            'hidden'   => $field->isHidden(),
        ]) ?>>
    <?php if (!$field->isRequired()) : ?>
        <option <?= $this->attr([
                    'value' => '',
                    'selected' => $field->value() === '',
                ]) ?>><?= $this->translate('page.none') ?></option>
    <?php endif ?>
    <?php if ($field->get('allowSite')) : ?>
        <option <?= $this->attr([
                    'value' => '.',
                    'selected' => $field->value() === '.',
                ]) ?>><?= $this->translate('panel.pages.newPage.site') ?> (/)</option>
    <?php endif ?>
    <?php foreach ($field->collection() as $page) : ?>
        <option <?= $this->attr([
                    'value' => $page->route(),
                    'selected' => $page->route() === $field->value(),
                    'data-allowed-templates' => $page->scheme()->options()->get('children.templates'),
                ]) ?>><?= str_repeat('— ', $page->level() - 1) . $this->escape($page->title()) ?></option>
    <?php endforeach ?>
</select>