Add Custom Data to WooCommerce Order via Custom Fields on Product Page

woo_add_custom_data_order.php

/*
*  Based on this post https://wisdmlabs.com/blog/add-custom-data-woocommerce-order-2/
*  Add custom data to order from the product page to admin order page in 
*	 See more useful snippets here -> https://wpuniverse.online/
*/

/** 
*	THE HOOKS 
*/

add_action('woocommerce_before_add_to_cart_button','wpu_add_custom_fields');
add_filter('woocommerce_add_cart_item_data','wpu_add_item_data',10,3);
add_filter('woocommerce_get_item_data','wpu_add_item_meta');
add_action( 'woocommerce_checkout_create_order_line_item', 'wpu_add_custom_order_line_item_meta');

/** 
*	THE HANLERS 
*/

// This will output before the "add to cart" button, making it a part of the "add to cart" form so it needs to be a proper form field
// i.e select, text input, checkbox etc...
function wpu_add_custom_fields () {
	// Do whatever you need here. e.g
	echo <input type="text" name="your_custom_data_name" value="your_custom_data_value">
}

// This will Add your custom data to the cart item
function wpu_add_item_data ($cart_item_data, $product_id, $variation_id) {
	  if(isset($_REQUEST['your_custom_data_name'])) {
        $cart_item_data['your_custom_data_name'] = sanitize_text_field($_REQUEST['your_custom_data_name']);
    }
		//As this is a filter - we need to return
    return $cart_item_data;
}
// This will display your custom meta in cart page
function wpu_add_item_meta ($item_data, $cart_item) {
	if(array_key_exists('your_custom_data_name', $cart_item)) {
		$custom_details = $cart_item['your_custom_data_name'];
		$item_data[] = array(
			'key'   => 'Name',
			'value' => $custom_details
		);
	}
return $item_data;
}
// Add Custom Details to Order Line Items
function wpu_add_custom_order_line_item_meta ($item, $cart_item_key, $values, $order) {
    if(array_key_exists('your_custom_data_name', $values))
    {
        $item->add_meta_data('_custom_name',$values['your_custom_data_name']);
    }
}