Online PHP editor | refs for TqgFA

<?php function array_flatten($array, $result = []) { if(!is_array($array)) { return false; } foreach($array as $key => $value) { if(is_array($value)) { $result = array_flatten($value, $result); } else { $result[$key] = $value; } } return $result; } $allowedKeys = [ 'firstname', 'middlename', 'street', 'lastname', 'housenumber', ]; $userdata = [ 'firstname' => 'first', 'middlename' => 'middle', 'lastname' => 'last', 'address' => [ 'street' => 'streeeeeet', 'housenumber' => '10' ] ]; $addresses = array_flatten($userdata); foreach($userdata as $key => $value) { if(!in_array($key, $allowedKeys)) { unset($userdata[$key]); } } var_dump($addresses);