function ideas_user_subscribe()
{

    if(!xarVarFetch('idea_id',   'id', $idea_id,   NULL, XARVAR_NOT_REQUIRED)) {return;}

	if (!isset($idea_id) || !is_numeric($idea_id)) {
		$msg = xarML('Invalid #(1) for #(2) function #(3)() in module #(4)',
					'idea_id', 'user', 'subscribe', 'ideas');
		throw new Exception($msg);
    }

	$uid = xarUserGetVar('uid');

	// Load up database details.
    $dbconn = xarDB::getConn();
    $xartable = xarDB::getTables();
	$prefix = xarDB::getPrefix();
    $subscriptions_table = $prefix . '_ideas_subscriptions';

    // Insert instance details.
    $query = 'INSERT INTO ' . $subscriptions_table . ' (
              role_id, idea_id,
              status
            ) VALUES (?, ?, ?)';
    $dbconn->Execute($query, array($uid, $idea_id, 1));

	$redirect = xarModURL('ideas','user','display',array('itemid' => $idea_id, 'name' => 'ideas_ideas'));

	xarResponse::redirect($redirect);
	return;

}