Woocommerce on Thank You Page get category to order_id

Question

I have a Tracking Code javascript from sendinblue.

I want to start an "automation" in this site for segmentation and, for that, I must send data from my site to sendinblue using its API.

In Wocommerce's "Thank You" page, I need to know the categories of products that a customer is buying and send this data to sendinblue via JS.

I have put this code in functions.php

add_action( 'woocommerce_thankyou', 'analisi' );    

function analisi($order_id) {
    $order = new WC_Order($order_id);   
    $items = $order->get_items();        

    foreach ($items as $item_id => $item_data)
    {
        //getting product object
        $_product = wc_get_product($item_data['item_meta']['_product_id'][0]);

        //getting all the product category
        $pro_cat_array = wp_get_post_terms($_product->ID, 'product_cat');

        $pro_cat = implode(',', $pro_cat_array);
        //storing all the line item as a string form
        $product_js[] = '{category:"' . $pro_cat . '"}';
    }
?>
    <!-- Paste Tracking Code Under Here -->
<script language="text/javascript">
sendinblue.track('categoria_acquisto', {    
  'categoria':'[<?= implode(',', $product_js) ?>]';  
});
</script>
<?php
}
?>

When I simulate the order and look at the HTML code the array (for sent categories) is empty.

    <script language="text/javascript">
sendinblue.track('categoria_acquisto', {    
  'categoria':'[{category:""}]';  
});
</script>

Answer 1

Not sure which version of WooCommerce you are using, but for WC > 3.0, you can use something like:

add_action( 'woocommerce_thankyou', 'analisi' );
function analisi( $order_id ) {
    $order      = wc_get_order( $order_id );
    $items      = $order->get_items();
    $product_js = array();

    /**
     * @var WC_Order_Item_Product $item_data
     */
    foreach ( $items as $item_id => $item_data ) {
        $product    = $item_data->get_product();
        $categories = array();

        $terms = get_the_terms( $product->get_id(), 'product_cat' );

        if ( is_wp_error( $terms ) || empty( $terms ) ) {
            continue;
        }

        foreach ( $terms as $term ) {
            $categories[] = $term->name;

            // Comment out the above and use the line below to have category IDs instead
            // $categories[] = $term->term_id;
        }

        $categories_list = implode( ',', $categories );
        if ( $categories_list ) {
            $product_js[] = '{category:"' . $categories_list . '"}';
        }
    }
    ?>
    <!-- Paste Tracking Code Under Here -->
    <script language="text/javascript">
        sendinblue.track('categoria_acquisto', {
            'categoria': '[<?php echo implode( ',', $product_js ) ?>]';
        })
        ;
    </script>
<?php } ?>