Get last result from mysqli_multi_query - php

Question

I'm creating PHP API for my Android application which will be used to scan QR codes. Part of that API is checking if scanned code is valid and can be scanned in a certain moment.
Whole checking part is a stored procedure in MariaDB database which is just executed by PHP script. Execution part in PHP is looking like this:
$sql = "CALL someProcedure('qr_code', #out); ";
$sql .= "SELECT #out AS `out`;";
if($conn->multi_query($sql)) {
while ($conn->more_results()) {
$conn->next_result();
}
$rs = $conn->store_result();
$row = $rs->fetch_assoc();
$odp = $row['out'];
if (!empty($rs)) {
$response['success'] = 1;
$response['message'] = $odp;
echo json_encode($response);
$rs->free();
} else {
$response['success'] = 0;
$response['message'] = mysqli_error($conn);
echo json_encode($response);
}
There are 4 results of that stored procedure:
scanned code doesn't exist,
scanned code is not an package (it is an articles code)
scanned code cannot be delivered just yet
scanning was successful
Now, when there is something wrong with the code, PHP part executes without a problem but if scanning is successful I would get a timeout (doesn't matter if it's default 30 seconds or 5 minutes).
The reason there is a timeout (I think) is that when scanning is successful there are some loops executed in Stored Procedure which may be returned in resultsets and choke PHP script ALTHOUGH when I execute that Stored Procedure in DBeaver (with exact same query as in PHP) there is no problem.
So, my question is what I can do about it? Removing the while loop in PHP script above makes the script execute without a problem (but I can't get the out parameter value.
Why not do two queries instead of one multi-query?
This is a respond to a comment by Rick James
Here's modified code:
$sql = "CALL ".$storedProcedure."(".$columns."); ";
$sql2 = "SELECT #out AS `out`;";
if($conn->query($sql)) {
if($rs = $conn->query($sql2)) {
$row = $rs->fetch_assoc();
$odp = $row;
if (!empty($odp)) {
$response['success'] = 1;
$response['message'] = $odp;
echo json_encode($response);
$rs->free();
} else {
$response['success'] = 0;
$response['message'] = mysqli_error($conn);
echo json_encode($response);
}
} else {
$response['success'] = 0;
$response['message'] = mysqli_error($conn);
echo json_encode($response);
}
And mysql error while executing the script:
{"success":0,"message":"Commands out of sync; you can't run this command now"}
The problem is when executing the second query.

Answer 1

I finally got it. All I had to do is to store results in every while loop iteration.
Here's how it looks now.
$sql = "CALL someProcedure('qr_code', #out); ";
$sql .= "SELECT #out AS `out`;";
if($conn->multi_query($sql)) {
while ($conn->more_results()) {
$rs = $conn->store_result();
$conn->next_result();
}
$rs = $conn->store_result();
$row = $rs->fetch_assoc();
$odp = $row['out'];
if (!empty($rs)) {
$response['success'] = 1;
$response['message'] = $odp;
echo json_encode($response);
$rs->free();
} else {
$response['success'] = 0;
$response['message'] = mysqli_error($conn);
echo json_encode($response);
}