Add a custom field to a product variation

//Display Fields add_action( 'woocommerce_product_after_variable_attributes', 'variable_fields', 10, 2 ); //JS to add fields for new variations add_action( 'woocommerce_product_after_variable_attributes_js', 'variable_fields_js' ); //Save variation fields add_action( 'woocommerce_process_product_meta_variable', 'variable_fields_process', 10, 1 ); function variable_fields( $loop, $variation_data ) { ?> <tr> <td> <div> <label></label> <input type="text" size="5" name="my_custom_field[]" value=""/> </div> </td> </tr> <tr> <td> <div> <label></label> </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; }