Rejecting in droppable

Hi,
I have a droppable that accepts ".newitem". Al running Ok, but now, i
want this droppable to accept this .newitem draggable only if certain
condition, for example if the body value is "text". If the text is
another would to reject this draggable. The problem is not to catch
and see the body text, but reject the draggable... Anybody knows how
to do this?