initJoomla.php

<?php
define('_JEXEC', 1);
define('JPATH_BASE', __DIR__);
require_once JPATH_BASE . '/includes/defines.php';
require_once JPATH_BASE . '/includes/framework.php';

// Boot the DI container
$container = \Joomla\CMS\Factory::getContainer();

/*
 * Alias the session service keys to the web session service as that is the primary session backend for this application
 *
 * In addition to aliasing "common" service keys, we also create aliases for the PHP classes to ensure autowiring objects
 * is supported.  This includes aliases for aliased class names, and the keys for aliased class names should be considered
 * deprecated to be removed when the class name alias is removed as well.
 */
$container->alias('session.web', 'session.web.site')
	->alias('session', 'session.web.site')
	->alias('JSession', 'session.web.site')
	->alias(\Joomla\CMS\Session\Session::class, 'session.web.site')
	->alias(\Joomla\Session\Session::class, 'session.web.site')
	->alias(\Joomla\Session\SessionInterface::class, 'session.web.site');

// Instantiate the application.
$app = $container->get(\Joomla\CMS\Application\SiteApplication::class);

// Set the application as global app
\Joomla\CMS\Factory::$application = $app;

var_dump($app);

For some reason this isn't working properly in my custom field class file where I'm trying to require a file from inside my template.

// the one $app you define above
$template = $app->getTemplate();

// should be myTemplateName
require_once JPATH_BASE .'/templates/'. $template . '/src/Helper/MyHelper.php';

Error:

InvalidArgumentException
Could not find template "myTemplateName".

Is this the only way to do Factory::getApplication('site') now?

Joomla 4.0.2

Something recently screwed it up - the getTemplate method is screwed in Joomla when using it like this, I have not had time to investigate yet.

Does this have to do with the fact that my template is installed via Extension Discovery?

Other bad things happen with this type of installation, for instance some language strings are not translated for some plugins, but IDK, I hope this gets fixed asap.

Thanks

No, it happens without any changes to Joomla core, when using AdministratorApplication (instead of site) it fails on trying to find 'isis'

I'll take a look later.