Change Quantity

{exp:cartthrob:change_quantity} is an immediate-execution single tag. It updates quantity for one cart row and can optionally redirect. It is not a form tag.

See also:

• update_cart_form
• cart_items_info
• delete_from_cart

Parameters

• row_id
• quantity
• return

row_id

Required. Row ID of the cart item to update.

row_id="{segment_3}"

quantity

Required. Target quantity for the cart row.

quantity="{segment_4}"

return

Optional redirect URL after processing. If omitted, no redirect occurs.

return="cart/index"

Behavior and Constraints

1. Looks up the cart item by row_id.
2. If the row exists, calls set_quantity(quantity) on that item.
3. Quantity handling is performed by item logic:
   • input is sanitized
   • value is normalized to absolute
   • fractional quantities are rounded down when fractional quantities are disabled
   • quantity <= 0 removes the row
4. If the row is not found, no item is changed.
5. Saves the cart.
6. Redirects only when return is provided.

Examples

Row link from cart_items_info

{exp:cartthrob:cart_items_info}
    <a href="{row_id_path=cart/change_quantity}/10">Change quantity to 10</a>
{/exp:cartthrob:cart_items_info}

Segment-driven update template

{exp:cartthrob:change_quantity row_id="{segment_3}" quantity="{segment_4}" return="cart/index"}

Set quantity to 0 (removes the row)

{exp:cartthrob:change_quantity row_id="{segment_3}" quantity="0" return="cart/index"}

Update without redirect

{exp:cartthrob:change_quantity row_id="{segment_3}" quantity="2"}