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/**
 * Custom Columns to Woo Orders Page
 * @SEE: http://stackoverflow.com/questions/13683162/woocommerce-show-custom-column
 */
add_filter( 'manage_edit-shop_order_columns', 'MY_COLUMNS_FUNCTION' );
function MY_COLUMNS_FUNCTION( $columns ) {
	$new_columns = ( is_array( $columns ) ) ? $columns : array();
	unset( $new_columns['order_actions'] );
	//edit this for you column(s)
	//all of your columns will be added before the actions column
	$new_columns['donation_code'] = 'Donation Code';
 
	$new_columns['order_actions'] = $columns['order_actions'];
 
	return $new_columns;
}
 
add_action( 'manage_shop_order_posts_custom_column', 'MY_COLUMNS_VALUES_FUNCTION', 2 );
function MY_COLUMNS_VALUES_FUNCTION( $column ) {
	global $post;
	$order = new WC_Order( $post->ID );
	$items = $order->get_items();
 
	//start editing, I was saving my fields for the orders as custom post meta
	//if you did the same, follow this code
	if ( $column == 'donation_code' ) {
		foreach ( $items as $item ) {
			$product_name = $item['name'];
			$product_id   = $item['product_id'];
 
			$donation_id = get_post_meta( $product_id, 'donation_code', true );
			echo $donation_id . "<br/>";
 
		}
	}
 
}