PHP function returning array index path

Question

I've been trying to write a PHP function which searches the id index valeus in array, and once found, returns the path which lead to it's discovery.

Take the following array:

    Array
(
    [0] => Array
        (
            [id] => 1
            [data] => Array
                (
                    [0] => Array
                        (
                            [id] => 8
                        )

                    [1] => Array
                        (
                            [id] => 9
                        )

                    [2] => Array
                        (
                            [id] => 10
                            [data] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 15
                                            [data] => Array
                                                (
                                                    [0] => Array
                                                        (
                                                            [id] => 22
                                                        )

                                                )

                                        )

                                    [1] => Array
                                        (
                                            [id] => 21
                                        )

                                )

                        )

                )

        )

)

If looking for [id] => 21 it would return array(1,10). However, in numerous attempts I have failed. The set path should be set to the index id. However, I cannot figure it out. Any words of guidance are much appreciated.

Answer 1

This functions returns array(1,10) for OP example

(will leave that other answer just in case someone will look for normal "path searching")

function search_data($needle, $haystack) {
    if (is_array($haystack)) {
        foreach($haystack as $data) {
            if ($data['id'] == $needle) return array();
            if (isset($data['data'])) {
                if (($path = search_data($needle, $data['data'])) !== false) return array_merge(array($data['id']), $path);
            }
        }
    }
    return false;    
}

Answer 2

This functions returns array(0,'data',2,'data',1,'id') for OP example (i.e. full path to value)

Function which searches for $key => $value pair in array and returns the path:

function array_search_r($key, $value, $haystack, $strict = null) {
    $strict = $strict ?: false;
    if (is_array($haystack)) {
        foreach($haystack as $k => $v) {
            if ($strict ? ($k === $key && $v === $value) : ($k == $key && $v == $value)) return array($k);
            if(($path = array_search_r($key, $value, $v, $strict)) !== false) return array_merge(array($k), $path);
        }
    }
    return false;
}