json_encode doesn't get echo'ed - php

Question

I'm trying to pull some records from the DB with the code below, but my echo json_encode($contacts); at the end of the code doesn't print anything. Nor does any echo put right above that.
<?php
require_once(dirname(__FILE__).'/ConnectionInfo.php');
//Set up our connection
$connectionInfo = new ConnectionInfo();
$connectionInfo->GetConnection();
if (!$connectionInfo->conn)
{
//Connection failed
echo 'No Connection';
}
else
{
//Create query to retrieve all contacts
$query = 'SELECT Numero_Leccion,Titulo_Leccion,Ejemplo_Leccion FROM leccion';
$stmt = sqlsrv_query($connectionInfo->conn, $query);
if (!$stmt)
{
//Query failed
echo 'Query failed';
}
else
{
$contacts = array(); //Create an array to hold all of the contacts
//Query successful, begin putting each contact into an array of contacts
while ($row = sqlsrv_fetch_array($stmt,SQLSRV_FETCH_ASSOC)) //While there are still contacts
{
//Create an associative array to hold the current contact
//the names must match exactly the property names in the contact class in our C# code.
$contact = array("Numero_Leccion"=>$row['Numero_Leccion'],"Titulo_Leccion"=>$row['Titulo_Leccion'],"Ejemplo_Leccion"=>$row['Ejemplo_Leccion']);
//Add the contact to the contacts array
array_push($contacts, $contact);
}
//Echo out the contacts array in JSON format
echo json_encode($contacts);
}
}
?>

Answer 1

Put error_reporting(E_ALL & ~E_NOTICE); ini_set('display_errors', '1'); somewhere on top of your script and see if there are any errors
(taken from Why echoing JSON encoded arrays won't produce any output)

Answer 2

Try this:
while ($row = sqlsrv_fetch_array($stmt,SQLSRV_FETCH_ASSOC))
{
$contacts[] = array("Numero_Leccion"=>$row['Numero_Leccion'],"Titulo_Leccion"=>$row['Titulo_Leccion'],"Ejemplo_Leccion"=>$row['Ejemplo_Leccion']);
}
header('Content-Type: application/json');
echo json_encode($contacts);