PHP mention system with usernames with space - php

Question

I wanted to know if it's possible to make a PHP mention system with usernames with space ?
I tried this
preg_replace_callback('##([a-zA-Z0-9]+)#', 'mentionUser', htmlspecialchars_decode($r['content']))
My function:
function mentionUser($matches) {
global $db;
$req = $db->prepare('SELECT id FROM members WHERE username = ?');
$req->execute(array($matches[1]));
if($req->rowCount() == 1) {
$idUser = $req->fetch()['id'];
return '<a class="mention" href="members/profile.php?id='.$idUser.'">'.$matches[0].'</a>';
}
return $matches[0];
It works, but not for the usernames with space...
I tried to add \s, it works, but not well, the preg_replace_callback detect the username and the other parts of the message, so the mention don't appear...
Is there any solution ?
Thanks !

Answer 1

I know you said that you just removed the ability to add a space, but I still wanted to post a solution. To be clear, I don't necessarily think you should use this code, because it probably is just easier to keep things simple, but I think it should work still.
Your major problem is that almost every mention will incur two lookups because #bob johnson went to the store could be either bob or bob johnson and there's no way to determine that without going to the databases. Caching will greatly reduce this problem, luckily.
Below is some code that generally does what you are looking for. I made a fake database using just an array for clarity and reproducibility. The inline code comments should hopefully make sense.
function mentionUser($matches)
{
// This is our "database" of users
$users = [
'bob johnson',
'edward',
];
// First, grab the full match which might be 'name' or 'name name'
$fullMatch = $matches['username'];
// Create a search array where the key is the search term and the value is whether or not
// the search term is a subset of the value found in the regex
$names = [$fullMatch => false];
// Next split on the space. If there isn't one, we'll have an array with just a single item
$maybeTwoParts = explode(' ', $fullMatch);
// Basically, if the string contained a space, also search only for the first item before the space,
// and flag that we're using a subset
if (count($maybeTwoParts) > 1) {
$names[array_shift($maybeTwoParts)] = true;
}
foreach ($names as $name => $isSubset) {
// Search our "database"
if (in_array($name, $users, true)) {
// If it was found, wrap in HTML
$ret = '<span>#' . $name . '</span>';
// If we're in a subset, we need to append back on the remaining string, joined with a space
if ($isSubset) {
$ret .= ' ' . array_shift($maybeTwoParts);
}
return $ret;
}
}
// Nothing was found, return what was passed in
return '#' . $fullMatch;
}
// Our search pattern with an explicitly named capture
$pattern = '##(?<username>\w+(?:\s\w+)?)#';
// Three tests
assert('hello <span>#bob johnson</span> test' === preg_replace_callback($pattern, 'mentionUser', 'hello #bob johnson test'));
assert('hello <span>#edward</span> test' === preg_replace_callback($pattern, 'mentionUser', 'hello #edward test'));
assert('hello #sally smith test' === preg_replace_callback($pattern, 'mentionUser', 'hello #sally smith test'));

Answer 2

Try this RegEx:
/#[a-zA-Z0-9]+( *[a-zA-Z0-9]+)*/g
It will find an at sign first, and then try to find one or more letter or numbers. It will try to find zero or more inner spaces and zero or more letters and numbers coming after that.
I am assuming the username only contains A-Za-z0-9 and space.