- json_encode: documentation ( source)
<?php
$arr = array(
"key1"=>"value1",
"key2"=>null,
"key3"=>array(
"subkey1"=>null,
"subkey2"=>"subvalue2"),
"key4"=>null);
echo json_encode(replace_null_with_empty_string($arr));
function replace_null_with_empty_string($array)
{
foreach ($array as $key => $value)
{
if(is_array($value))
$array[$key] = replace_null_with_empty_string($value);
else
{
if (is_null($value))
$array[$key] = "";
}
}
return $array;
}