Like the json_decode idea, wrote this:
function a($json) {
return json_decode($json, true); //turn true to false to use objets instead of associative arrays
}
//EXAMPLE
$cat = 'meow';
$array = a('{"value1":"Tester",
"value2":"'.$cat.'",
"value3":{"valueX":"Hi"}}');
print_r($array);