Pull Request for Issue #41183 .

Summary of Changes

The banners module supports using banners by tag search or keywords. When the banners model is building the query for it, there is a reg-expression to search for words. This regex seems not be compatible with MySql version 8.0.4 and newer.

The SQL query, which is created, is something like: Where metakey regexp('[[:<:]]Mo[[:>:]]')
"Mo" is the keyword to search for.

Executing it on MySql 8.0.4 or any newer version, it throws the error "Illegal argument to a regular expression.".
I think the correct reg-expression must be: Where metakey regexp('\\bMo\\b')

In the MySql manual https://dev.mysql.com/doc/refman/8.0/en/regexp.html there is the explanation about the switch from the Henry Spencer's implementation to the ICU compatible implementation:

MySQL implements regular expression support using International Components for Unicode (ICU), which provides full Unicode support and is multibyte safe. (Prior to MySQL 8.0.4, MySQL used Henry Spencer's implementation of regular expressions, which operates in byte-wise fashion and is not multibyte safe.

Further information in the web can for example be found here:
https://bugs.mysql.com/bug.php?id=106504
https://stackoverflow.com/questions/59998409/error-code-3685-illegal-argument-to-a-regular-expression

System information:
Joomla: The site which had/has those issues had version 5 and is in the meantime migrated to 6 (where the errors still appear).
DB type: mysql
DB version: 8.0.42
PHP-Version: 8.4.7

Background information:
I use a custom component which calls in a view $this->getDocument()->setMetaData('keywords', $currentKeywords);
With this approach, the banners module gets those keywords in its BannersHelper method getBanners() line 45 with:
$keywords = explode(',', $app->getDocument()->getMetaData('keywords'));

With this Pull Request the reg-expression will be surrounded with a db type and version check, which makes sure the correct expression is used for both versions.

In the same part of the banners model there is

• another fix for a null ref deprecation warning from PHP 8:

  Deprecated
  : str_starts_with(): Passing null to parameter #2 ($needle) of type string is deprecated in
  [root]\components\com_banners\src\Model\BannersModel.php on line 219

• a fix for a PHP 8 warning:

  Warning
  : foreach() argument must be of type array|object, false given in
  [root]\components\com_banners\src\Model\BannersModel.php on line 275

Testing Instructions

Honestly, I don't know how I can provide the keywords with the Joomla standard components. So the easiest way to reproduce is:

1. Activate maximum error reporting in the system configuration.
2. In the banners component configuration, make sure in Tab "Client" the "Keyword Prefix" is empty.
3. Create banner 1
   Under Tab Publishing, set a keyword into "Keywords": Mo
   set "Use Own Prefix" to Yes
   set "Keyword Prefix" to: Mo
4. Create banner 2, with the same settings as mentioned for banner 1.
5. Create banner 3, with the same settings as mentioned for banner 1, but set "Keywords": Di
6. Create a site module banners
   Set a client
   Set a category.
   Set "Select by Keyword" to Yes.
7. Now edit the module_banners in BannersHelper method getBanners() line 45, and replace
   $keywords = explode(',', $app->getDocument()->getMetaData('keywords'));
   with
   $keywords = ['Mo'];
8. Clear cache.
9. Open that menu item from the site and check the output.

Actual result BEFORE applying this Pull Request

• No banners are visualized. The getItems method has catched the error "Illegal argument to a regular expression." but returned no banner data.
• The PHP 8 deprecation warning "...Passing null to parameter #2 ($needle) of type string is deprecated..." is displayed.
• The PHP 8 warning "...foreach() argument must be of type array|object, false given..." is displayed.

Expected result AFTER applying this Pull Request

• Banner 1 and Banner 2 are visualized. (banners having "Keywords": Mo)
• None of the two PHP 8 warnings are displayed.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed