Club Drupal

/**

 * Allows modules to confirm that an order may proceed to checkout.

 *

 * If any implementation of this hook returns TRUE, the given order can proceed

 * to checkout. However, if no implementations of this hook exist and return

 * TRUE, the checkout router will simply redirect away to the front page.

 *

 * @param $order

 *   The order being confirmed for checkout.

 *

 * @return

 *   Boolean value indicating whether or not the order can proceed to checkout.

 */

function hook_commerce_checkout_order_can_checkout($order) {

  // Allow orders with one or more product line items to proceed to checkout.

  // If there are no line items on the order, redirect away.

  $wrapper = entity_metadata_wrapper('commerce_order', $order);

  if (commerce_line_items_quantity($wrapper->commerce_line_items, commerce_product_line_item_types()) > 0) {

    return TRUE;

  }

}