Autoload external library in Joomla 5 component

Question

In my Joomla 4 component I successfully used the Mpdf library. Since migrating to Joomla 5, the library does not initialise properly. This is the setup that worked in Joomla 4:

class MyModel extends BaseModel
{

   public function generatePDF($data)
   {
      $mpdf = new \Mpdf\Mpdf([]); 
      ...
   }
}

The composer.json which loads the Mpdf version working with PHP 8.2 https://mpdf.github.io/about-mpdf/requirements-v7.html:

{
  "config": {
    "vendor-dir": "admin/vendor",
    "platform": {
      "php": "8.2.0"
    }
  }, "require: {
    "mpdf/mpdf": "^8.1.3"
  }
}

The vendor classes are located in /administrator/components/com_mycomponent/vendor which contains the /autoload.php as well.

In the mycomponent.xml the vendor files are registered like this:

<administration>
  <files folder="admin">
     ...
     <folder>vendor</folder>
  </files
</administration>

What is the proper way to autoload external libraries in Joomla 5?

Answer 1

Solution:

There is one missing piece of the puzzle. The component must have access to the autoloader. To do this, you need to place this line of code on my component's service provider - like this:

...
use Joomla\DI\ServiceProviderInterface;

//require_once __DIR__ . '/../vendor/autoload.php'; // This did not work in my case
require_once JPATH_ADMINISTRATOR . '/components/com_mycomponent/vendor/autoload.php';

/**
 * The service provider.
 *
 * @since  4.0.0
 */
return new class() implements ServiceProviderInterface
{
   ...