How to make a dependent select list based on the data inside?

Question

PHP

How can I make a dependent select list based on the select data?
I wrote the first part of the list, but the second part does not want to be shown through value, I don't understand how to write php code correctly.

<?php $biolink_pages = require APP_PATH . 'includes/biolink_pages.php'; ?>
<div class="form-group">
<label for="settings_pages"><i class="fa fa-fw fa-user fa-sm mr-1"></i> <?= language()->link->settings->font ?></label>
<select id="settings_page_type" name="page_type" class="form-control">
<?php foreach($biolink_pages as $key => $value): ?>
<option value="<?= $key ?>" <?= $data->link->settings->page_type == $key ? 'selected="selected"' : null?>><?= $key ?></option>
                                    <?php endforeach ?>
                                </select>
                            </div>

this piece of code is displayed and written to the database, but when I try to pull out other values ​​from page_type, it does not write, it only displays. biolink_pages.php

file code

<?php

return [
    'businesses' => [       
    ],

    'community_organization' => [
    ],

    'interest' => [
    ],

    'media' => [
    ],

    'public_figure' => [
        'actor',
    'artist',
    'athlete',
    'author',
    'band',
    'blogger',
    'chef',
    'comedian',
    'dancer',
    'designer',
    'fashion-designer',
    'digital-creator',
    'editor',
    'entrepreneur',
    'fashion model',
    'film-director',
    'fitness model',
    'gamer',
    'journalist',
    'motivational-speaker',
    'musician',
    'musician-band',
    'news personality',
    'orchestra',
    'producer',
    'scientist',
    'spiritual-leader',
    'sports-promoter',
    'talent-agent',
    'video-creator',
    'writer'
    ],
];

here is a piece of code that is displayed, but does not write the value, + is not tied to the choice of the first

<div id="" class="form-group">
                                <label for="settings_pages"><i class="fa fa-fw fa-user fa-sm mr-1"></i> <?= language()->link->settings->font ?></label>
                                <select id="settings_page_category" name="page_category" class="form-control">
                                    <?php foreach($biolink_pages['public_figure'] as $page_category): ?>
                                        <option value="<?= $page_category ?>" <?= $data->link->settings->page_category == $page_category ? 'selected="selected"' : null?>><?= $page_category ?></option>
                                    <?php endforeach ?>
                                </select>
                            </div>

It is necessary that when choosing public_figure, a list appears with values ​​inside, as well as for other choices.

Answer 1

here is a piece of code that is displayed, but does not write the value

Perhaps it does not lie in the same form as the first select?

+ is not tied to the choice of the first

How did you try to bind it? You stupidly brought one more select to the page, didn't you?