The #mention system does not produce the correct output - php

Question

The following function is not getting a correct results:
function getMentions($content) {
global $db;
$mention_regex = "/#+([a-zA-Z0-9-_]+)/"; //mention regrex to get all #texts
$regexIt = preg_match_all($mention_regex, $content, $matches);
if ($regexIt) {
foreach ($matches[1] as $key => $match) {
if ($key === 0) continue;
$mentioned[] = mysqli_real_escape_string($db, $match[0]);
$match_user = mysqli_query($db, "SELECT user_id, user_name FROM dot_users WHERE user_name IN ('" . implode("','", $matches[1]) . "')") or die(mysqli_error($db));
$userDeti = mysqli_fetch_array($match_user, MYSQLI_ASSOC);
echo $userDeti['user_id'];
echo $userDeti['user_name'];
$match_search = '#' . $match . '';
$match_replace = '<a target="_blank" href="' . $userDeti['user_name'] . '">#' . $userDeti['user_name'] . '</a>';
if (isset($userDeti['user_name'])) {
$content = str_replace($match_search, $match_replace, $content);
}
}
}
return $content;
}
For example, I want to print the user_name and user_id on the screen, but it does not print.
echo $userDeti['user_id']; // echo is empty
echo $userDeti['user_name']; //echo is empty output
Can you tell me what I'm doing wrong or incomplete?

Answer 1

My untested suggestion...
function getMentions($content) {
global $db; // I would rather this be passed as a function argument
if (preg_match_all("/\B#\K[\w-]+/", $content, $matches)) {
if (!$result = mysqli_query($db, "SELECT user_id, user_name FROM dot_users WHERE user_name IN ('" . implode("','", $matches[0]) . "')")) {
// error
} else {
foreach ($result as $row) {
$content = preg_replace("~\B#{$row["user_name"]}\b~", "#{$row["user_name"]}", $content);
}
}
}
return $content;
}
There may be typos, but the general idea is there. Capture mentions and try to avoid emails, look up the ids, replace all mentions.