Question

I’m creating a little php file to get mysql rows for my android application.
to retrieve each single row i use:

    $q=mysql_query($sql, $this->conn) or die (mysql_error());
while($e=mysql_fetch_assoc($q)) {
      $output[]=$e;
    }
print(json_encode($output));

but sometimes it returns me an inconsistent output.

Here’s an example:
The row:

id=1 (correct) – name=”name1″ (correct) – price=200 (correct) – price2=null (correct) – area=null (NOT CORRECT) because area has a value of “Centro Città” .. and so on..

How can i resolve this problem?

EDIT: the value is

[{“id”:”84″,”idutente1″:null,”idutente2″:null,”idutente3″:null,”idutente4″:null,”idutente5″:null,”idagente”:null,”annuncio”:”0″,”archiviato”:”0″,”dataarchiviazione”:”2012-07-05 13:31:19″,”tipoimmobile”:”Residenziale”,”metodo”:”Vendita”,”area”:null,”presentazione”:”1″,”homepage”:”1″,”mappa”:”1″,”nome”:”Piazza Umberto I”,”luogo”:”Crotone”,”descrizione”:”60 mq composto da due vani oltre servizi, centralissimo buono per ufficio.”,”descdettagliata”:”
L’appartamento è diviso in due vani con cucina e bagno.</p>\r\nPosto nel pieno centro e vicinissimo al lungomare Regina Margherita.</p>\r\n Ottimo condominio. Libero e disponibile da subito. /p>”,”vani”:”2″,”prezzo”:”87000″,”prezzo1″:”0″,”prezzo2″:”0″,”prezzo3″:”0″,”prezzo4″:”0″,”prezzo5″:”0″,”metriquadri”:”58″,”stato”:”In buono stato”,”riscaldamento”:”Autonomo”,”classeenergetica”:”Non dotato”,”piano”:”Primo/secondo/terzo”,”indicazioni”:””,”mutuo”:”No”,”banca”:””,”importo”:””,”finalita”:””,”tipologia”:””,”ammortamento”:””,”visite”:”20″,”timestamp”:”2012-06-25 10:48:01″,”nomefile”:”HPIM2268.jpg”}]

area field is not null, but is “Centro Città”. The rest is correct.
I tried to show only the “area” field with a mysql_fetch_assoc($query) and it returns me the correct result: “Centro Città”. This problem is only with json_encode.

The SQL Variabile is:

$sql = sprintf("SELECT i.*, f.nomefile FROM immobili i LEFT JOIN foto f on(i.id=f.idimmobile AND f.copertina=1) WHERE i.id=%s", $_GET['id']);

This is only an example, if i ask other rows, the area field returns correctly also with json_encode and other fields return null. Could it be a problem related with the strings and the text format?

Answer 1

It’s an encoding problem. json_encode() accepts only UTF-8 strings, and returns null if a string is not valid UTF-8.

You can fix this by converting the encoding of your data before passing it to json_encode. Take a look at iconv() or mb_convert_encoding().

For example, assuming your data is encoded in latin1:

$e = array_map(function($string) {
    return iconv("iso-8859-1", "utf-8", $string);
}, $e);

$output[] = $e;

Or if you have php < 5.3:

function cb($string) {
    return iconv("iso-8859-1", "utf-8", $string);
}

$e = array_map('cb', $e);

$output[] = $e;