How to edit 'status' attribute triggered by action?

Tuesday 05 December 2006 7:19:49 pm

For example,

for online shopping, there is an item

previously, its status is available. {$item.data_map.status = 0}

when someone buy this item, its status should be changed to unavailable.

something like {set $item.data_map.status = 0}}

but how to perform this action,

/* status is an attribute of the class item, and is stored in database */

Thanks very much