CycleJson.php

$json = '{"foo":"bar",
          "order":["first", "second", "third"],
          "pairs":[{"id":"0"}, {"id":"1"}]}';

function doObject($__obj){
    $__obj = cycleObject($__obj);
    return $__obj;
}

function cycleObject($__obj){
    foreach($__obj as $key => &$val){
        if(is_object($val)) {
            cycleObject($val);
        }
        if(is_array($val)) {
            foreach($val as &$v) {
                if(is_object($v) || is_array($v)) {
                    cycleObject($v);
                } else {
                    $v .= '-ok';
                }
            }
        }
        if(is_string($val)) {
            $val .= '-ok';
        }
    }
    return $__obj;
}

$obj = doObject(json_decode($json));
var_dump($obj);