problem with using extract php function?

Question

 <?php  
 function check($user_id, $topic_id){

        $query = mysql_query("SELECT user_id, topic_id FROM sa where topic_id='$topic_id' and user_id='$user_id'");
        if (mysql_num_rows($query)==1){



           return 'you have already voted';
        }
        else {

            $against = ' <li>
    <button type="submit" value="Actions" class="against" title="against">
      <i></i><span>Against</span></button>
          </li>';

            $support ='<li>
            <button type="submit" value="Actions" class="support" title="support">
                <i></i>
                <span>Support</span>
            </button>
        </li>';
            return compact('support', 'against');
        }

extract(check($_SESSION['user_id'], $topicId));

  echo $against;
  echo $support;
?>

i keep getting this error:

Warning: extract() [function.extract]: First argument should be an array 

Answer 1

First, function definition is not closed in your code (no closing "}")

Second, your function returns string if user has already voted - in this case PHP would obviously say "First argument should be an array" on extract() function call.

Generally, I'd recommend not to use compact-extract construction, but use structures or associative arrays as return value instead. In this case behavior would be much clearer.

Answer 2

The extract function expects an array. You're passing it the results of your check function, which is sometimes an array

return compact('support', 'against');

but sometimes a string.

return 'you have already voted';

So, I imagine you're seeing the error when the first return statements is executed.

Answer 3

Maybe something like this is better:

function check($user_id, $topic_id){
    $query = mysql_query("SELECT user_id, topic_id FROM sa where topic_id='$topic_id' and user_id='$user_id'");
    if (mysql_num_rows($query)==1){
       return array('error'=>'you have already voted');
    }
    else {
        $against = ' <li>
<button type="submit" value="Actions" class="against" title="against">
  <i></i><span>Against</span></button>
      </li>';

        $support ='<li>
        <button type="submit" value="Actions" class="support" title="support">
            <i></i>
            <span>Support</span>
        </button>
    </li>';
        return compact('support', 'against');
    }
}

$result = check($_SESSION['user_id'], $topicId);

if(isset($result['error'])) {
    echo $result['error'];
}
else {
    echo $result['against'];
    echo $result['support'];
}

You could also consider to use exceptions.

Answer 4

So as it suggests: Warning: extract() [function.extract]: First argument should be an array

Try following:

$arr = check($_SESSION['user_id'], $topicId);
if(is_array($arr)) {
  extract($arr);
  echo $against;
  echo $support;
} else {
  echo $arr;
}