Add a Custom Field to WooCommerce Product Variations

WooCommerce variable products support many common options by default, including SKU, price, stock quantity, product image, dimensions, and weight. In most cases, those options are enough to run a standard store. But sometimes they are not enough. For example, if an ecommerce site stores products in different warehouses across the country, we may need to add a “storage location” field to each variation so we can handle products and orders more effectively. I have not researched whether other open-source ecommerce systems support this easily, but in WooCommerce custom development this is very simple to implement.

Add a custom field to WooCommerce variable products

Place the following code in the functions.php file of the WooCommerce theme you are currently using.

function variable_fields( $loop, $variation_data ) {
?> 
 <tr>
   <td>
     <div>
       <label><?php _e( 'Storage location', 'woocommerce' ); ?></label>
       <input type="text" size="5" name="my_custom_field[<?php echo $loop; ?>]" value="<?php echo $variation_data['_my_custom_field'][0]; ?>"/>
     </div>
   </td>
 </tr>
<?php
}

function variable_fields_js() {
?>
<tr>    <td>       <div>         <label><?php _e( 'Storage location', 'woocommerce' ); ?></label>         <input type="text" size="5" name="my_custom_field[' + loop + ']" />       </div>    </td> </tr><?php
}

function variable_fields_process( $post_id ) {
 if (isset( $_POST['variable_sku'] ) ) :
   $variable_sku = $_POST['variable_sku'];
   $variable_post_id = $_POST['variable_post_id'];
   $variable_custom_field = $_POST['my_custom_field'];
   for ( $i = 0; $i < sizeof( $variable_sku ); $i++ ) :
      $variation_id = (int) $variable_post_id[$i];
      if ( isset( $variable_custom_field[$i] ) ) {
        update_post_meta( $variation_id, '_my_custom_field', stripslashes( $variable_custom_field[$i] ) );
     }
   endfor;
 endif;
}

Read the custom field from a WooCommerce variation

The custom field we added is ultimately just a standard WordPress custom field, so when reading it we can simply use get_post_meta.

global $product; 
$available_variations = $product->get_available_variations();

foreach ($available_variations as $prod_variation) :
    $post_id = $prod_variation['variation_id'];
    $post_object = get_post($post_id);
    $my_custom_field = get_post_meta( $post_object->ID, '_my_custom_field', true);
end foreach;

As a WordPress ecommerce plugin, WooCommerce provides a very rich and flexible set of extension points, which makes secondary development and customization very convenient. If you need a custom WooCommerce theme or plugin, you can contact WordPress Zhiku directly.