part-code.php

<?php

    foreach( $order-> get_items() as $item_key => $item_values ):

    $item_id = $item_values->get_id();
    $item_name = $item_values->get_name(); // Name of the product
    $item_type = $item_values->get_type(); // Type of the order item ("line_item")
    $product_id = $item_values->get_product_id(); // the Product id
    $wc_product = $item_values->get_product(); // the WC_Product object
    $item_data = $item_values->get_data();
    $product_name = $item_data['name'];
    $product_id = $item_data['product_id'];
    $variation_id = $item_data['variation_id'];
    $quantity = $item_data['quantity'];
    $tax_class = $item_data['tax_class'];
    $line_subtotal = $item_data['subtotal'];
    $line_subtotal_tax = $item_data['subtotal_tax'];
    $line_total = $item_data['total'];
    $line_total_tax = $item_data['total_tax'];
    $order_id = $item_data['order_id'];
    
    if ($product_id == 37) {
       
    } else if ($product_id == 50) {

    $patt_carrier = ''; // This needs to be the value of the custom attibute 'carrier'
    $patt_template = ''; // This needs to be the value of the custom attibute 'template'

        $product_type = "PICKANDPACK";
        $postData['bundles'][] = [ 
            'type' => $product_type,
            'items' => [
                'bom' => [
                    [
                        'type' => 'CARRIER',
                        'quantity' => '1',
                        'stockId' => $patt_carrier,
                        'metadata' => [
                            'template' => $patt_template,
                            'mergeFields' => [
                                'to' => '',
                                'msg' => '',
                                'giftAmount' => '',
                                'from' => ''
                            ]
                        ]
                    ],
                    ],
                ],
            'delivery' => [
                'method' => 'SHIPPING METHOD HERE', // I need the shipping method name here
                'shippingAddress' => [
                    'firstname' => '',
                    'lastname' => '',
                    'addressLine1' => '',
                    'addressLine2' => '',
                    'town' => '',
                    'county' => '',
                    'postcode' => ''
                ]
            ]

        ];
    }

        
 
endforeach;