Question

I want to apply a function to each element/prop of an object but it seems array_walk_recursive() does not work on object. i.e:

if( $re = $con->query("SELECT id, created_date, contents FROM " . 
                      POST_DATA . " WHERE type = 'news' ORDER BY ".
                      "created_date DESC LIMIT $amount") ) {
    if( $re->num_rows != 0 ) {
        while( $ob = $re->fetch_object() ) {
            $ob = array_walk_recursive( $ob, "_output" );
            print_r($ob);
            die();
        }
    }
}

would simply return ‘1’.

How might I resolve this?

Answer 1

It’s actually returning a value of True for array_walk_recursive. If you look at the function’s documentation, you’ll see that what this method is doing is calling the function _output for each item and key in the object.

You should also have some code that looks similar to this, I would imagine, to get it to work correctly:

function _output($data, $key) {
    echo "For the key $key, I got the data: ";
    print_r($data);
}

Where _output is called because that is the stringified name that you gave in the array_walk_recursive function. That should print your values to the screen.

---

Edit:

It seems that I’m not actually answering what you were originally wanting to do, though. If you’re wanting to apply a function to every element of an array, I would suggest that you look at array_map. You can use array_map like this:

function double($item) {
    return 2 * $item;
}

array_map('double', $item);

Ultimately, if the recursion is something that you desire, you could probably do something like this:

function callback($key, $value) {
    // do some stuff
}

function array_map_recursive($callback, $array) {
   $new_array = array()
   foreach($array as $key => $value) {
      if (is_array($value)) {
          $new_array[$key] = array_map_recursive($callback, $value);
      } else {
          $new_array[$key] = call_user_func($callback, $key, $value);
      }
   }
   return $new_array;
}

array_map_recursive('callback', $obj);

That would return another array like $obj, but with whatever the callback was supposed to do.