PHP json_encode function returns blank {}

Question

I am trying to use an AJAX call to fetch some data and return multiple pieces of data to the caller through JSON. It works for certain tests that include simple output. But when one of the elements being returned is HTML, then it does not work. Any thoughts on this?

// get_answer() pulls some HTML back from an XML document
$answer = $_SESSION['quiz_session']->get_answer();
// test output to make sure everything is working
echo $answer;
/** sample output **
 * 
 <div>
 <p>
 <b>
 <span class="gloss-def">a downward slope</span>
 </b>
 </p>
 <p>Because the village was situated on the 
 <i>declivity</i> of a hill, it never flooded.
 </p>
 <p>
 <i>Synonyms: decline; descent; grade; slant; tilt</i>
 </p>
 </div>
 *
 ** end sample output **/
 echo json_encode($answer);
 // will output {}

• Pekka: json_encode() will do that if it encounters non-UTF8 characters in the input. Your example doesn't seem to contain any such characters, though.
• Rudie: Try utf8_encode($answer) before encoding to json.
• Pekka: That'll be useful only if the fetched data happens to be encoded in ISO-8859-1/latin1, though. Better to try and find out what exactly is going on first
• user555: I might be too tiered now but since when does the superglobal $_SESSION have class methods?
• user1527739: Adding utf8_encode($answer) does make it work! Thank you for the suggestion. Do you know what character exactly it was that makes it require such a encoding function? Line breaks? Semi Colons?

Answer 1

Try adding $answer to and stdClass or an array, like

echo json_encode(array("answer"=>$answer));

• user1527739: Unfortunately that does not help, the output is {"answer":{}}
• vrunoa: then it must be the encoding problem you mention above