Multisort a 2 deep array - php

Question

Consider the following multisort method. In this case I have a array of items with a specific start date. Example array is shown:
0 -> array('title' => 'hello',
'attributes' => array('id' => 4, 'startdate' => '2013-06-11')),
1 -> array('title' => 'hello second entry',
'attributes' => array('id' => 6, 'startdate' => '2013-04-11'))
You can see that the 2nd entry should come before the first. Using my call currently will not work because It only checks to depth 1 of the array.
$albums = $this->multiSort($items, "SORT_ASC", 'startdate', true);
How would be the best way to modify this method to have a depth search on the items in the array. Even better would be to be able to specific the depth key. I would like to avoid having to add additional parameters to the method.
I could call the method like so and then write a for loop to get the key data, but having nested for loops is not something I want to do.
$albums = $this->multiSort($items, "SORT_ASC", array('attributes', 'startdate') , true);
What is the best way to optimize this method for my case?
public function multiSort($data, $sortDirection, $field, $isDate) {
if(empty($data) || !is_array($data) || count($data) < 2) {
return $data;
}
foreach ($data as $key => $row) {
$orderByDate[$key] = ($isDate ? strtotime($row[$field]) : $row[$field]);
}
if($sortDirection == "SORT_DESC") {
array_multisort($orderByDate, SORT_DESC, $data);
} else {
array_multisort($orderByDate, SORT_ASC, $data);
}
return $data;
}

Answer 1

UPDATED. This allows you to pass in a string for field that is delimited and is a path to your desired field.
$items = Array();
$items[0] = array('title' => 'hello',
'attributes' => array('id' => 4, 'startdate' => '2013-06-11'));
$items[1] = array('title' => 'hello second entry',
'attributes' => array('id' => 6, 'startdate' => '2013-04-11'));
function multiSort($data, $sortDirection, $field, $isDate) {
if(empty($data) || !is_array($data) || count($data) < 2) {
return $data;
}
// Parse our search field path
$parts = explode("/", $field);
foreach ($data as $key => $row) {
$temp = &$row;
foreach($parts as $key2) {
$temp = &$temp[$key2];
}
//$orderByDate[$key] = ($isDate ? strtotime($row['attributes'][$field]) : $row['attributes'][$field]);
$orderByDate[$key] = ($isDate ? strtotime($temp) : $temp);
}
unset($temp);
if($sortDirection == "SORT_DESC") {
array_multisort($orderByDate, SORT_DESC, $data);
} else {
array_multisort($orderByDate, SORT_ASC, $data);
}
return $data;
}
$albums = multiSort($items, "SORT_ASC", 'attributes/startdate', true);
print_r($albums);
Ouput:
Array
(
[0] => Array
(
[title] => hello second entry
[attributes] => Array
(
[id] => 6
[startdate] => 2013-04-11
)
)
[1] => Array
(
[title] => hello
[attributes] => Array
(
[id] => 4
[startdate] => 2013-06-11
)
)
)