Add to cart fule

gistfile1.txt

function commerce_installments_rules_action_info() {
  $actions['commerce_installments_action_add_to_cart'] = array(
    'label' => t('Add a product to the cart'),
    'group' => t('Commerce Installments'),
    'parameter' => array(
      'product' => array(
        'type' => 'commerce_product',
        'label' => t('Product'),
        ),
      'line_item_type' => array(
        'type' => 'text',
        'label' => t('Line Item Type'),
        'options' => 'commerce_installments_line_item_type_options'
      ),
    ),
  );

  return $actions;
}

/**
 * Returns an array of line item names keyed by line item type, suitable for use
 * with a select element #options.
 */
function commerce_installments_line_item_type_options() {
  $types = commerce_line_item_types();
  $options = array_intersect_key(commerce_line_item_type_get_name(), drupal_map_assoc($types));
  return $options;
}

/**
 * Rules Action: Add a product to the cart.
 *
 * @param $product
 *   The product to add.
 */
function commerce_installments_action_add_to_cart($product, $line_item_type) {
  // Create the new product line item of the same type.
  $line_item = commerce_product_line_item_new($product, 1, 0, array(), $line_item_type);

  // Process the unit price through Rules so it reflects the user's actual
  // purchase price.
  rules_invoke_event('commerce_product_calculate_sell_price', $line_item);

  // Only attempt an Add to Cart if the line item has a valid unit price.
  $line_item_wrapper = entity_metadata_wrapper('commerce_line_item', $line_item);

  if (!is_null($line_item_wrapper->commerce_unit_price->value())) {
    // Add the product to the specified shopping cart.
    $form_state['line_item'] = commerce_cart_product_add(
      $form_state['values']['uid'],
      $line_item,
      isset($line_item->data['context']['add_to_cart_combine']) ? $line_item->data['context']['add_to_cart_combine'] : TRUE
    );

    drupal_set_message(t('%title added to <a href="!cart-url">your cart</a>.', array('%title' => $product->title, '!cart-url' => url('cart'))));
  }
  else {
    drupal_set_message(t('%title could not be added to your cart.', array('%title' => $product->title)), 'error');
  }
}

/************* And here is the component in use ***************/
/*
{ "rules_add_item_to_cart" : {
    "LABEL" : "Add Item to Cart",
    "PLUGIN" : "action set",
    "REQUIRES" : [ "commerce_installments" ],
    "USES VARIABLES" : {
      "commerce_product" : { "label" : "Product", "type" : "commerce_product" },
      "line_item_type" : { "label" : "Line Item Type", "type" : "text" }
    },
    "ACTION SET" : [
      { "commerce_installments_action_add_to_cart" : {
          "product" : [ "commerce-product" ],
          "line_item_type" : [ "line_item_type" ]
        }
      }
    ]
  }
}
*/