PHP - Find parent key of array
I'm trying to find a way to return the value of an array's parent key.
For example, from the array below I'd like to find out the parent's key where $array['id'] == "0002". The parent key is obvious because it's defined here (it would be 'products'), but normally it'd be dynamic, hence the problem. The 'id' and value of 'id' is known though.
[0] => Array
(
[data] =>
[id] => 0000
[name] => Swirl
[categories] => Array
(
[0] => Array
(
[id] => 0001
[name] => Whirl
[products] => Array
(
[0] => Array
(
[id] => 0002
[filename] => 1.jpg
)
[1] => Array
(
[id] => 0003
[filename] => 2.jpg
)
)
)
)
)
Solution 1:
A little crude recursion, but it should work:
function find_parent($array, $needle, $parent = null) {
foreach ($array as $key => $value) {
if (is_array($value)) {
$pass = $parent;
if (is_string($key)) {
$pass = $key;
}
$found = find_parent($value, $needle, $pass);
if ($found !== false) {
return $found;
}
} else if ($key === 'id' && $value === $needle) {
return $parent;
}
}
return false;
}
$parentkey = find_parent($array, '0002');
Solution 2:
Since you have a tree structure either of a BFS or DFS can do it. Since the structure is variable a recursive solution would work well. Simply return a sentinel when you find the value, then return the key in the caller.