Facebook api call in php returns empty

Question

I have result of $result = $facebook->api($params); How to extract information from it? Cant decode it using json_decode, gets an error the parameter is string. Searched a lot for the solution, couldn't find any related information.

EDIT

$params = array(

 'method' => 'fql.query',
 'query' => "SELECT uid,pic_square,name,devices FROM user WHERE uid IN (SELECT uid2 FROM friend WHERE uid1=me())",
    );
  $result = $facebook->api($params);

Could this return empty? Without showing any error? What am I doing wrong?

Answer 1

Turns out, I was testing it using a test user which had no friends. That was the reason why the response was an empty array.

Answer 2

A simple debugging technique is to var_dump the variables to see where you're going wrong like so.

echo '<pre>'; //just to make the var_dump pretty in the browser
var_dump([variable you want to look into]);
exit(); //does let anything after it display

Assuming $params is formatted correctly, I would try applying the var_dump to $result after the code you just submitted. Then you'll see the format of the string is and hopefully why you aren't able to decode it. The above is a great debugging technique in general.