[RESOLVED] need help with function!!!

[zzz]

I have a function that generates 5 character long random key.

         function generator($lenght=5)
	{
	     for($i = 0; $i <= $lenght; $i++)
	     {
	          $uniqueKey .= chr(rand(97,122));
	     }
	     return $uniqueKey;
	}
	$uKey = generator();

Now I need to add step 2 -- query my db to see if this key is already taken. If yes, repeat the first step, generate new key and then check again.

Here's how I query my db:

if ($uKey == $db->get_var("SELECT key FROM t1 WHERE key = '".$uKey."' ") )
{
   // key exists
} else {
   // key does not exist
}

I can't put it together for a world... Really need some serious help!

echo $usrKey; // abcdefgh

[NogDog]

You could put the ID generation and the DB check within a loop, something like this:

function generator($lenght = 5, $maxTries=100)
{
   $found = false;
   $count = 0;
   while (!$found) {
      if(++$count > $maxTries)
      {
         user_error("There was a problem generating your ID, please try again.");
         return false;
      }
      for ($i = 0; $i <= $lenght; $i++) {
         $uniqueKey.= chr(rand(97, 122));
      }
      // check if this key is OK, then...
      if($ok)
      {
         $found = true;
      }
   }
   return $uniqueKey;
}

[zzz]

I like this. So I just need to add db query like this?

function generator($lenght = 5, $maxTries=100, $db)
{
   $found = false;
   $count = 0;
   while (!$found) {
      if(++$count > $maxTries)
      {
         user_error("There was a problem generating your ID, please try again.");
         return false;
      }
      for ($i = 0; $i <= $lenght; $i++) {
         $uniqueKey.= chr(rand(97, 122));
      }
      // check if this key is OK, then...

  if ($uniqueKey == $db->get_var("SELECT key FROM t1 WHERE key = '". $uniqueKey."' ") )
  {
        // key exists
        $found = true;
  } else {
        // key does not exist
        $found = false;
  }
   }
   return $uniqueKey;
} 

$myKey = generator();

[Installer]

That returns the query result rather than a string. Here's another way (assuming $db->get_var() returns or resolves to a boolean):

function generator($db, $length = 5, $max_tries = 100)
{
    $alpha = implode('', range('a', 'z'));
    $count = 0;
    do {
        $rand_str = substr(str_shuffle($alpha), 0, $length);
        $exists   = $db->get_var("SELECT key FROM t1 WHERE key = '" . $rand_str . "'");
    } while ($exists && ($count++ < $max_tries));  

    return $exists ? false : $rand_str;
}

Usage:

$user_key = generator($db_obj);
if (!$user_key) {
    echo 'Error generating user key.';
    // Some code
}

[zzz]

This key generation should be taking place without any user involvement. It needs to keep trying until a it creates a new unique key that has not been used before. There's really no use for me to alert the user about the outcome.

It has to be simple and solid. Max_tries set at 100 is more then enough, even if I have millions of users. So far I only have about 6K keys to worry about so even without a check I'm OK but it can dupe any minute without a check and that will be really bad for me... 🙁

[Installer]

This key generation should be taking place without any user involvement.

Then don't involve the user.

It needs to keep trying until a it creates a new unique key that has not been used before.

Then have it keep trying until it creates a new unique key.

There's really no use for me to alert the user about the outcome.

Then don't alert the user.

It has to be simple and solid. Max_tries set at 100 is more then enough, even if I have millions of users. So far I only have about 6K keys to worry about so even without a check I'm OK but it can dupe any minute without a check and that will be really bad for me...

You're ok without a check, but it could be really bad without a check? (And isn't checking what the query is about?)

[zzz]

Yes to all.

My only hesitations is switching the way the key is generated from what I had to a new one. I suppose it is irrelevant, since there will be a check in place to guard against the duplicates...

Which one is faster? Is there any way to guestimate? Or it it really insignificant?

I'm not challenging any of the code, just would like to understand it better.