I am trying to limit the creation of a node reference to 1 per user and per referenced node. More specifically: I have a content type named Debate and another one called Vote. Vote has a node reference field (from URL widget) called *debate_ref* to the Debate type. What i'm trying to achieve is for each user and for each debate to have only one vote i.e. when a user tries to create a 2nd vote node on the same debate node then he will recieve a message saying "You have already voted!".
"Unique field" module does the job but after the user attempts to save his 2nd vote node. What i would like to achieve is to deny access to the user who attempts to re-visit the "node/add/vote/nid" form if he has already voted for the specific debate.