note 129083 added to function.array-column

If you want to preserve the array keys AND you want it to work on both object properties and array elements AND you want it to work if some of the arrays/objects in the array do not have the given key/property defined, basically the most ROBUST version you can get, yet quick enough: <?php function array_column_keys(array|ArrayAccess $arr, string $col) { // like array_columns but keeps the keys //to make it work for objects and arrays return array_map(fn($e) => (is_countable($e) ? ($e[$col]??null) : null) ?: (is_object($e) ? $e->$col : null), $arr); } ?> If a key/property is undefined, the value in the result array will be NULL. You can use array_filter() to filter those out if needed. <?php class a { public string $a = 'property a'; public string $b = 'property b'; } $a1 = new a; $a2 = new a; $a2->a = 'plop'; $b = ['one'=> ['a'=>'plop'], 3 => $a1, 4 => $a2, 5 =>[], 'kud'=>new a]; return array_column_keys($b, 'a'); ?> Returns: Array ( [one] => plop [3] => property a [4] => something else [5] => [kud] => property a ) ---- Server IP: 45.112.84.4 Probable Submitter: 45.91.157.134 (proxied: 85.145.75.206) ---- Manual Page -- https://php.net/manual/en/function.array-column.php Edit -- https://main.php.net/note/edit/129083 Del: integrated -- https://main.php.net/note/delete/129083/integrated Del: useless -- https://main.php.net/note/delete/129083/useless Del: bad code -- https://main.php.net/note/delete/129083/bad+code Del: spam -- https://main.php.net/note/delete/129083/spam Del: non-english -- https://main.php.net/note/delete/129083/non-english Del: in docs -- https://main.php.net/note/delete/129083/in+docs Del: other reasons-- https://main.php.net/note/delete/129083 Reject -- https://main.php.net/note/reject/129083 Search -- https://main.php.net/manage/user-notes.php