problem with using extract php function? - php

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

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 2

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 3

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 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;
}