CakeProducts/templates/element/Products/form.php

<?php
/**
 * @var \App\View\AppView $this
 * @var \Cake\Datasource\EntityInterface $product
 * @var \Cake\Datasource\EntityInterface $productCategory
 * @var \Cake\Collection\CollectionInterface|string[] $productCatalogs
 * @var \Cake\Collection\CollectionInterface|string[] $productCategories
 */
?>
<h4 class="mb-4">Basic Info</h4>

<?php
echo $this->Form->control('name');
echo $this->Form->control('product_catalog_id', [
        'empty' => 'Select a Catalog',
    'options' => $productCatalogs,
    'hx-trigger' => 'change, load delay:500ms',
    'hx-get' => $this->Url->build([
        'controller' => 'ProductCategories',
        'action' => 'select',
        '?' => ['form' => 'product'],
        0 => $productCategory ? $productCategory->product_catalog_id : '',
    ]),
    'hx-target' => '#product_category_id',
]);
echo $this->Form->control('product_category_id', [
    'options' => [],
    'empty' => true,
    'id' => 'product_category_id',
    'hx-trigger' => 'change, load delay:1s',
    'hx-get' => $this->Url->build([
        'controller' => 'ProductCategoryAttributes',
        'action' => 'form',
        '?' => ['form' => 'product'],
        0 => $productCategory ? $productCategory->product_catalog_id : '',
    ]),
    'hx-target' => '#product-attributes-container',
]);
echo $this->Form->control('product_type_id');
?>
<hr>
<h4 class="mb-4">Product Attributes</h4>
<div
        id="product-attributes-container"
        class="container"
    <?php if ($product->isNew()) : ?>

        hx-get="<?= $this->Url->build([
            'controller' => 'ProductCategoryAttributes',
            'action' => 'form',
        ]); ?>"
        hx-trigger="change target:#product_category_id from:body"
        hx-target="this"
        hx-include="#form, #product_category_id"
        hx-swap="innerHTML"
    <?php endif; ?>
>
    <?php if ($product->hasValue('product_attributes')) : ?>
        <?php
        $cnt = 0;
        foreach ($product->product_attributes as $productAttribute) {
            $prefix = 'product_attributes.' . $cnt . '.';

            echo $this->element('ProductCategoryAttributes/product_form', [
                'productCategoryAttribute' => $productAttribute->hasValue('product_category_attribute') ? $productAttribute->product_category_attribute : null,
                'productAttribute' => $productAttribute,
                'cnt' => $cnt,
            ]);
            $cnt++;
        } ?>
    <?php endif; ?>
</div>