Pimcore 5 Basic Language Switcher with Twig Extension

language-switcher.html.twig

{% for link, text in get_localized_links(document) %}
  {% set isActive = (app.request.locale is defined and app.request.locale == text) ? 'class="is-active"' : '' %}
  <a href="{{ link }}" {{ isActive|raw }}>{{ text|upper }}</a>{% if not loop.last %} |{% endif %}
{% endfor %}

LanguageSwitcherExtension.php

/**
 * Provides get_localized_links function in the Twig.
 *
 * Class LanguageSwitcherExtension
 */
class LanguageSwitcherExtension extends \Twig_Extension
{
    /**
     * Pimcore documents service which provide needed methods.
     *
     * @var Document\Service
     */
    private $documentService;

    /**
     * Request helper instance.
     *
     * @var RequestHelper
     */
    private $requestHelper;

    /**
     * Localized links array
     *
     * @var array
     */
    private $localizedLinks = [];

    /**
     * Rel alternate languages links array
     *
     * @var array
     */
    private $relAlternateLinks = [];

    /**
     * Initialize needed services for extension.
     *
     * @param Document\Service $documentService
     * @param RequestHelper $requestHelper
     */
    public function __construct(Document\Service $documentService, RequestHelper $requestHelper)
    {
        $this->documentService = $documentService;
        $this->requestHelper = $requestHelper;
    }

    /**
     * Provides language links array.
     *
     * @param Document $document
     *
     * @return array
     */
    public function getLocalizedLinks(Document $document): array
    {
        if (count($this->localizedLinks)) {
            return $this->localizedLinks;
        }

        $translations = $this->documentService->getTranslations($document);

        $links = [];
        foreach (Tool::getValidLanguages() as $language) {
            $target = '/' . $language;
            if (isset($translations[$language])) {
                $localizedDocument = Document::getById($translations[$language]);
                if ($localizedDocument) {
                    $target = $localizedDocument->getFullPath();
                }
            }

            $links[$target] = $language;
        }

        return $links;
    }

    /**
     * Provides alternative versions of document (translated in other languages)
     *
     * @param Document $document
     *
     * @return array
     */
    public function getRelAlternate(Document $document)
    {
        if ($this->getRelAlternateLinks()) {
            return $this->getRelAlternateLinks();
        }

        $translations = $this->documentService->getTranslations($document);

        $result = [];
        foreach ($translations as $language => $documentId) {
            if ($this->requestHelper->getRequest()->getLocale() == $language) {
                continue;
            }

            $localizedDocument = Document::getById($documentId);
            if ($localizedDocument instanceof Document) {
                $result[$language] = $localizedDocument->getFullPath();
            }
        }

        return $result;
    }

    /**
     * Returns a list of functions to add to the existing list.
     *
     * @return \Twig_SimpleFunction[]
     */
    public function getFunctions(): array
    {
        return [
            new \Twig_Function('get_localized_links', [$this, 'getLocalizedLinks']),
            new \Twig_Function('get_rel_alternate', [$this, 'getRelAlternate'])
        ];
    }

    /**
     * setLocalizedLinks to use in lang switch
     *
     * @param array $localizedLinks
     *
     * @return LanguageSwitcherExtension
     */
    public function setLocalizedLinks(array $localizedLinks): LanguageSwitcherExtension
    {
        $this->localizedLinks = $localizedLinks;

        return $this;
    }

    /**
     * set links for rel alternate
     *
     * @param array $relAlternateLinks
     *
     * @return LanguageSwitcherExtension
     */
    public function setRelAlternateLinks(array $relAlternateLinks): LanguageSwitcherExtension
    {
        foreach ($relAlternateLinks as $language => $link) {
            if ($this->requestHelper->getRequest()->getLocale() == $language) {
                continue;
            }

            $this->relAlternateLinks[$language] = $link;
        }

        return $this;
    }

    /**
     * getRelAlternateLinks
     *
     * @return array
     */
    public function getRelAlternateLinks(): array
    {
        return $this->relAlternateLinks;
    }
}