So, this seems like a rather simple task but i'veI've been stuck on it for a while.
I need either in hook_node_presavehook_node_presave
or in hook_node_submit hook_node_submit
(but NOT in hook_node_validatehook_node_validate
) to check for a field value in a node and according to that value choose whether or not to cancel the node saving procedure.
How do I do that? (The canceling part, not the checking part ;) )