Badge system and storing conditions as variables?

Question

I'm trying to write a piece of code that checks a users stats, be that their points, rank or num_friends and in turn awards them a badge similar to that used in SO. The system is set so when a task (vote up, comment, etc.) is completed by a user, their user_id is recorded and queued to be evaluated at 5 min intervals by a cron job. Is this the most efficient way of doing this? I saw the other post about badges but am not sure if this is the method that was selected as the preferred way.

Another question I have is about actually checking these variables (points, rank, num_friends) against the user. I have a number of badges and want to allow admins to add their own where they select a variable, the operator (==, >=, etc.) and the value it's set to. How do I evaluate that in an IF conditional statement? I tried using SWITCH for the operators but can't get the variables to be evaluated correctly, like:

function checkbadges($userid,$points,$rank,$friends){
    global $database;

    $q = $database->db_query("SELECT * FROM badges");
    while($bq = $database->db_fetch_assoc($q)) {
        switch($bq[badge_sign]) {
          case "1":
              if($bq[badge_var] == $bq[badge_value])
                  givebadge($userid, $bq[badge_id]);
            break;
          case "2":
              if($bq[badge_var] >= $bq[badge_value]))
                  givebadge($userid, $bq[badge_id]);
            break;
          case "3":
              if($bq[badge_var] <= $bq[badge_value]))
                  givebadge($userid, $bq[badge_id]);
            break;
          case "4":
              if($bq[badge_var] != $bq[badge_value]))
                  givebadge($userid, $bq[badge_id]);
            break;
        }
    }
}

I think I have to use eval() but I'm not sure how, any help would be appreciated!

Answer 1

If $bq['badge_var'] is a string which is a valid variable name in the current scope, you can just do this:

$value = ${ $bq['badge_var'] };

It might be safer and easier to extend if you pass an array to checkbadges() instead:

function checkbadges($userid,$userdata){
    global $database;
    $q = $database->db_query("SELECT * FROM badges");
    while($bq = $database->db_fetch_assoc($q)) {
        $currentValue = $userdata[ $db['badge_var'] ];
        $requiredValue = $db['badge_value'];
        $issueBadge = false;
        switch($bq['badge_sign']) {
          case "1":
              $issueBadge = ( $currentValue == $requiredValue );  
          break;
          case "2":
              $issueBadge = ( $currentValue >= $requiredValue );  
            break;
          case "3":
              $issueBadge = ( $currentValue <= $requiredValue );  
            break;
          case "4":
              $issueBadge = ( $currentValue != $requiredValue );  
          break;
        }

        if ($issueBadge) {
            givebadge($userid, $bq['badge_id']);
        }
    }
}

where $userdata is something like this:

array( 'points' => 1 , 'friends' => 10, 'rank' => 10 );

You can then extend the available variables without modifying the function

Answer 2

Which is the expected value and the observed value of the variable you are not getting the right value for?

Additionally, its better practice to use:

$arr['key']

instead of

$arr[key]

as PHP will evaluate it first as a constant which is bad practice, see PHP Reference: Arrays