Summary of Changes

The legacy way to load a model is JModelLegacy::getInstance which is widely used in Joomla 3. This doesn't work anymore for components which are namespaced in Joomla 4 as models are loaded there through the component MVC factory. This pr adds a functionality to also load namespaced models the old way. The following code works both on J3 and J4 with this patch, without, the model can't be found on J4.

JModelLegacy::addIncludePath(JPATH_ADMINISTRATOR . '/components/com_contact/models', 'ContactModel');
$model   = JModelLegacy::getInstance('Contact', 'ContactModel', ['ignore_request' => true]);

Additionally it fixes the indexer purge task on the command line.

Testing Instructions

On the command line execute the following command in the joomla root:
php cli/finder_indexer.php --purge

Actual result BEFORE applying this Pull Request

The following error is printed:

Smart Search INDEXER
============================
Saving filters
- number of saved filters: 0
Clear index
Error {#191
  #message: "Call to a member function purge() on bool"
  #code: 0
  #file: "/var/www/html/Projects/cms4/cli/finder_indexer.php"
  #line: 360
  trace: {
    /var/www/html/Projects/cms4/cli/finder_indexer.php:360 {
      FinderCli->purge()^
      › // Attempt to purge the index.
      › $return = $model->purge();
      › 
    }
    /var/www/html/Projects/cms4/cli/finder_indexer.php:183 { …}
    /var/www/html/Projects/cms4/libraries/src/Application/CliApplication.php:241 { …}
    /var/www/html/Projects/cms4/cli/finder_indexer.php:514 { …}
  }
}

Expected result AFTER applying this Pull Request

The purging process doesn't fail:

Smart Search INDEXER
============================
Saving filters
- number of saved filters: 0
Clear index
- index clear successful
Starting Indexer
Setting up Smart Search plugins
Setup 5 items in 0.293 seconds.
 * Processed batch 1 in 0.411 seconds.
 * Skipping pause, as previous batch had a very low processing time (0.411s < 1s)
Restoring filters
- number of filters restored: 0
Total Processing Time: 0.705 seconds.
Peak memory usage: 16,777,216 bytes

Documentation Changes Required

None, as it is not documented in the potential issues doc that JModelLegacy::getInstanceis not working for namespaced components.