TYPO3 Extbase get record with language different than FE or 0

ext_localconf.php

<?php

/** @var \TYPO3\CMS\Extbase\SignalSlot\Dispatcher $signalSlotDispatcher */
$signalSlotDispatcher = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\\CMS\\Extbase\\SignalSlot\\Dispatcher');
$signalSlotDispatcher->connect(
	'TYPO3\\CMS\\Extbase\\Persistence\\Generic\\Backend',
	'beforeGettingObjectData',
	'Onedrop\\Common\\Service\\ExtbaseForceLanguage',
	'forceLanguageForQueries'
);

ExtbaseForceLanguage.php

<?php
namespace Onedrop\Common\Service;
/***************************************************************
 *  Copyright notice
 *
 *  (c) 2015 Hans Höchtl <[email protected]>
 *  All rights reserved
 *
 *  This script is part of the TYPO3 project. The TYPO3 project is
 *  free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  The GNU General Public License can be found at
 *  http://www.gnu.org/copyleft/gpl.html.
 *  A copy is found in the textfile GPL.txt and important notices to the license
 *  from the author is found in LICENSE.txt distributed with these scripts.
 *
 *
 *  This script is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  This copyright notice MUST APPEAR in all copies of the script!
 ***************************************************************/

use TYPO3\CMS\Core\SingletonInterface;
use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Extbase\Object\ObjectManager;
use TYPO3\CMS\Extbase\Persistence\Generic\Session;
use TYPO3\CMS\Extbase\Persistence\QueryInterface;

class ExtbaseForceLanguage implements SingletonInterface
{

	protected $overrideLanguage = FALSE;
	protected $languageUid = 0;
	protected $languageMode = NULL;
	protected $languageOverlayMode = FALSE;

	/**
	 * This method is registered on the Signal beforeGettingObjectData of the Extbase Generic Backend
	 * to override the returned model language
	 *
	 * @param QueryInterface $query
	 * @return QueryInterface
	 */
	public function forceLanguageForQueries(QueryInterface $query) {
		if (!$this->overrideLanguage) {
			return [$query];
		}
		$querySettings = $query->getQuerySettings();
		$querySettings->setLanguageUid($this->languageUid);
		$querySettings->setLanguageMode($this->languageMode);
		$querySettings->setLanguageOverlayMode($this->languageOverlayMode);
		$query->setQuerySettings($querySettings);
		return [$query];
	}

	/**
	 * @return boolean
	 */
	public function isOverrideLanguage()
	{
		return $this->overrideLanguage;
	}

	/**
	 * When changing the override language, we clear the persistence session of extbase,
	 * otherwise the non translated objects would be returned (cache).
	 *
	 * @param boolean $overrideLanguage
	 * @return void
	 */
	public function setOverrideLanguage($overrideLanguage)
	{
		$this->overrideLanguage = $overrideLanguage;
		/** @var ObjectManager $objectManager */
		$objectManager = GeneralUtility::makeInstance(ObjectManager::class);
		/** @var Session $persistenceSession */
		$persistenceSession = $objectManager->get(Session::class);
		$persistenceSession->destroy();
	}

	/**
	 * @return int
	 */
	public function getLanguageUid()
	{
		return $this->languageUid;
	}

	/**
	 * @param int $languageUid
	 * @return void
	 */
	public function setLanguageUid($languageUid)
	{
		$this->languageUid = $languageUid;
	}

	/**
	 * @return mixed
	 */
	public function getLanguageMode()
	{
		return $this->languageMode;
	}

	/**
	 * @param mixed $languageMode
	 * @return void
	 */
	public function setLanguageMode($languageMode)
	{
		$this->languageMode = $languageMode;
	}

	/**
	 * @return mixed
	 */
	public function getLanguageOverlayMode()
	{
		return $this->languageOverlayMode;
	}

	/**
	 * @param mixed $languageOverlayMode
	 * @return void
	 */
	public function setLanguageOverlayMode($languageOverlayMode)
	{
		$this->languageOverlayMode = $languageOverlayMode;
	}

}

SomeController.php

<?php
namespace Onedrop\Common\Controller;
/***************************************************************
 *  Copyright notice
 *
 *  (c) 2015 Hans Höchtl <[email protected]>, Onedrop Solutions
 *  All rights reserved
 *
 *  This script is part of the TYPO3 project. The TYPO3 project is
 *  free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  The GNU General Public License can be found at
 *  http://www.gnu.org/copyleft/gpl.html.
 *  A copy is found in the textfile GPL.txt and important notices to the license
 *  from the author is found in LICENSE.txt distributed with these scripts.
 *
 *
 *  This script is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  This copyright notice MUST APPEAR in all copies of the script!
 ***************************************************************/
use TYPO3\CMS\Core\Resource\ResourceFactory;
use TYPO3\CMS\Core\Utility\GeneralUtility;
use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;

/**
 * Class SomeController
 *
 * @package Onedrop\Common\Controller
 */
class SomeController extends ActionController
{
	/**
	 * @var \Onedrop\Common\Domain\Repository\SomeRepository
	 * @inject
	 */
	protected $someRepository;
	/**
	 * @var \Onedrop\Common\Service\ExtbaseForceLanguage
	 * @inject
	 */
	protected $extbaseForceLanguageService;

	public function someAction($langUid = 0) {
  		$this->extbaseForceLanguageService->setOverrideLanguage(true);
		$this->extbaseForceLanguageService->setLanguageUid($langUid);
			
		$extbaseRecordWithOverlayDifferentThanFeLanguage = $this->someRepository->findByUid(1);
			
		$this->extbaseForceLanguageService->setOverrideLanguage(false);
	}

}

I had to add a small, really really dirty hack, to make it work in an importer that is started by a command controller:

if (!isset($GLOBALS['TSFE'])) {
    $GLOBALS['TSFE'] = (object) ['gr_list' => ''];
}

So great!!
you saved my day! Thx a lot!

Even in 2021 this saved me a lot of time, thank you!

Does it works with nested objects? Are they also retrieved in forced language of parent object (lazy loading with ObjectStorage)?
I have used your solution directly in a repository function but the nested objects are still in standard language:

public function findByUidAndLanguage($uid, $languageUid=0)
{
$objectManager = GeneralUtility::makeInstance(ObjectManager::class);
/** @var Session $persistenceSession */
$persistenceSession = $objectManager->get(Session::class);
$persistenceSession->destroy();
$query = $this->persistenceManager->createQueryForType(Description::class);
$query->getQuerySettings()->setRespectSysLanguage(false);
$query->getQuerySettings()->setRespectStoragePage(false);
$query->getQuerySettings()->setLanguageUid($languageUid);
$query->getQuerySettings()->setLanguageOverlayMode(false);
$query->getQuerySettings()->setLanguageMode('content_fallback');
$query->matching($query->equals('uid', $uid));
$object = $query->execute()->getFirst();
$test = $object->getNestedObject(); // <-- They are not in language of object !! :-(
}

I have found the mistake myself. Al sub/nested objects will be retrieved forced in language which are loaded between setOverrideLanguage(true) and setOverrideLanguage(false). My single function does not work!

Thanks for the code. It works great on a single showbyUid but I can't get it working on a listview. I have mixed language records and in the list query it simply does not work :(