LanguageService

This class is used to translate strings in plain PHP. For examples see Localization in PHP. A LanguageService should not be created directly, therefore its constructor is internal. Create a LanguageService with the LanguageServiceFactory.

In the backend context a LanguageService is stored in the global variable $GLOBALS['LANG']. In the frontend a LanguageService can be accessed via the contentObject:

class LanguageService
Fully qualified name
\TYPO3\CMS\Core\Localization\LanguageService

Main API to fetch labels from XLF (label files) based on the current system language of TYPO3. It is able to resolve references to files + their pointers to the proper language. If you see something about "LLL", this class does the trick for you. It is not related to language handling of content, but rather of labels for plugins.

Usually this is injected into $GLOBALS['LANG'] when in backend or CLI context, and populated by the current backend user. Do not rely on $GLOBAL['LANG'] in frontend, as it is only available under certain circumstances! In frontend, this is also used to translate "labels", see TypoScriptFrontendController->sL() for that.

As TYPO3 internally does not match the proper ISO locale standard, the "locale" here is actually a list of supported language keys, (see Locales class), whereas "English" has the language key "default".

Further usages on setting up your own LanguageService in BE:

$languageService = GeneralUtility::makeInstance(LanguageServiceFactory::class)
    ->createFromUserPreferences($GLOBALS['BE_USER']);
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public lang

This is set to the language that is currently running for the user

sL ( ?string $input)

Main and most often used method.

Resolve strings like these:

'LLL:EXT:core/Resources/Private/Language/locallang_core.xlf:labels.depth_0'
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This looks up the given .xlf file path in the 'core' extension for label labels.depth_0

Only the plain string contents of a language key, like "Record title: %s" are returned. Placeholder interpolation must be performed separately, for example via sprintf(), like LocalizationUtility::translate() does internally (which should only be used in Extbase context)

Example: Label is defined in EXT:my_ext/Resources/Private/Language/locallang.xlf as:

<trans-unit id="downloaded_times">
    <source>downloaded %d times from %s locations</source>
</trans-unit>
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The following code example assumes $this->request to hold the current request object. There are several ways to create the LanguageService using the Factory, depending on the context. Please adjust this example to your use case:

$language = $this->request->getAttribute('language');
$languageService =
  GeneralUtility::makeInstance(LanguageServiceFactory::class)
  ->createFromSiteLanguage($language);
$label = sprintf(
     $languageService->sL(
         'LLL:EXT:my_ext/Resources/Private/Language/locallang.xlf:downloaded_times'
     ),
     27,
     'several'
);
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This will result in $label to contain 'downloaded 27 times from several locations'.

param $input

Label key/reference

Returns
string
overrideLabels ( string $fileRef, array $labels)

Define custom labels which can be overridden for a given file. This is typically the case for TypoScript plugins.

param $fileRef

the fileRef

param $labels

the labels

getLocale ( )
Returns
?\TYPO3\CMS\Core\Localization\Locale

Example: Use

EXT:my_extension/Classes/Controller/ExampleController.php (not Extbase) 
<?php

use Psr\Http\Message\ServerRequestInterface;
use TYPO3\CMS\Core\Localization\LanguageServiceFactory;

final class ExampleController
{
    private ServerRequestInterface $request;

    public function __construct(
        private readonly LanguageServiceFactory $LanguageServiceFactory,
    ) {}

    public function processAction(
        string $content,
        array $configurations,
        ServerRequestInterface $request,
    ): string {
        $this->request = $request;

        // ...
        $content .=  $this->getTranslatedLabel(
            'LLL:EXT:my_extension/Resources/Private/Language/locallang.xlf:labels.exampleLabel',
        );
        // ...

        return $content;
    }

    private function getTranslatedLabel(string $key): string
    {
        $language =
            $this->request->getAttribute('language')
                ?? $this->request->getAttribute('site')->getDefaultLanguage();
        $languageService = $this->LanguageServiceFactory
            ->createFromSiteLanguage($language);

        return $languageService->sL($key);
    }
}
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