Create a lightweight commerce cart block

The .module file

We build a custom block and use hook_theme to render the cart data. Usually a view is made to create a custom shopping cart block. However, a custom block to render number of items and the total price of an order is more exciting to make and more performant than a view.

As page cache is disabled by commerce, which sets cookies, only block cache is activated. By setting cache to DRUPAL_NO_CACHE, cache is disabled for this particular block.

/**
 * Implements hook_block_info().
 */
function commerce_general_block_info() {
  $blocks['commerce_general_shopping_cart'] = array(
    'info' => t('CG - Shopping cart'),
    'title' => '',
    'theme' => variable_get('theme_default', 'bartik'),
    'region' => 'header',
    'cache' => DRUPAL_NO_CACHE,
    );

  return $blocks;
}

/**
 * Implements hook_block_view().
 */
function commerce_general_block_view($delta = '') {
  switch ($delta) {
    case 'commerce_general_shopping_cart':
    return array(
      'subject' => t('CG - Shopping cart'),
      'content' => theme(
        'commerce_general_shopping_cart',
        array(
          'cart' =>_commerce_general_get_shopping_cart_data()
          )
        ),
      );
    break;
  }
}

/**
 * Implements hook_theme().
 */
function commerce_general_theme($existing, $type, $theme, $path) {
  return array(
    'commerce_general_shopping_cart' => array(
      'template' => 'commerce_general_shopping_cart',
      'arguments' => array('cart' => array())
      )
    );
}

/**
 * Retrieve the current customers lightweight shopping cart data.
 */
function _commerce_general_get_shopping_cart_data() {

  global $user;
  $data = array();
  $order = commerce_cart_order_load($user->uid);
  if ($order) {
    $quantity = 0;
    $wrapper = entity_metadata_wrapper('commerce_order', $order);
    $line_items = $wrapper->commerce_line_items;
    $data['quantity'] = commerce_line_items_quantity($line_items, commerce_product_line_item_types());
    $total = commerce_line_items_total($line_items);
    $data['price'] = commerce_currency_format($total['amount'], $total['currency_code']);
  }

  return $data;
}

The template file

<div>
  <?php if(!isset($cart['quantity'])): ?>
    <?php print t('Your shopping cart is empty'); ?>
  <?php else: ?>
    <?php print format_plural($cart['quantity'], t('1 item'), t('@count items'));?>
    <?php print t('Order total: ') ?><?php print $cart['price']; ?>
  <?php endif; ?>
  <a href="/cart"><?php print t('Cart'); ?></a>
</div>