What server-side (and client-side) validation is performed in the customer's shopping cart?

In addition to the client-side JavaScript validation of products in the shopping cart, the following server-side validation is also performed in the customer’s shopping cart:

• If an item is out of stock, the item is moved to the customer’s Wish List.
• If one of the product options is out of stock, the item is moved to the customer’s Wish List.
• If an option group is removed or changed, the item is removed from the cart.
• If an option name is changed, the new name is updated in the shopping cart.
• If a surcharge is changed, the price is updated in the cart.
• If a surcharge option changed from each item in basket to once per item, or vice versa, the price is updated.
• If a product question is removed or changed—and if the item in the cart has that question answered by the customer—the item is removed from the cart. If the product does not have that question answered by the customer in cart, the item remains in the cart.
• If an item is removed from the Inventory Manager (deleted), that item is removed from the cart.
• If a quantity discount group or discount amount is changed, the price is reset in the cart.
• If a customer is assigned with a discount percentage in the Customer Manager, the cart is updated with that price for all items as soon as the user logs in.
• If a customer is assigned to a Customer Group, the pricing of that group is applied to all items in the cart.
• If a bundled sub-item is deleted from the system, the main bundle and all its associated sub-items are removed from the cart.
• If a customer group price is assigned for a product—and if the customer belongs to that group—the price in the cart for that item is updated.
• If a product variant group is removed from the system and added again with the same name, the item in the cart is updated with the new surcharge (if any changes in surcharge; otherwise, the item remains unchanged in the cart).
• If the price of an item is changed, the new price is applied in the cart.
• If a product has a membership price, and if that price is changed, a new membership price is applied in the cart.
• Based on the Hide products if not In Stock setting, the product inventory and options inventory are validated. If no stock available, the item is moved to the customer’s Wish List.

The following conditions are NOT validated:

• If an item is invisible (made invisible after adding it to the shopping cart), the item will remain in the cart (we do not validate the product visibility in the shopping cart once an item is added to the cart).
• If a product question is changed to mandatory or if the size of the answer field is changed, no changes are made in the cart and the existing item will remain.
• If a product bundle is changed by removing a sub-item and adding a new sub-item, this is not validated this in the cart.
• The customer’s Wish List is not validated. However, when an item is moved from the Wish List to the shopping cart, the item is validated.