$data = stripslashes(file_get_contents("php://input"));
$get_data = json_decode($data);

$value1 = $get_data->{'part_no'};

$data = stripslashes(file_get_contents("php://input"));
$get_data = json_decode($data);

$value2 = $get_data->{'item_no'};

$data = file_get_contents("php://input");
$get_data = json_decode($data);
$value1 = $get_data->part_no ?? null;
$value2 = $get_data->item_no ?? null;