When EXT:seo is installed, TYPO3 renders hreflang and canonical tags for you. Most of the time the default output is exactly right. But there is always one project where it is not: a language which is online but not ready for search engines, a partner site on another system that should appear in the hreflang list, or a filter parameter that should never end up in the canonical URL.<\/p>\n
In older TYPO3 versions people solved such things with TypoScript tricks, XCLASSes or by switching off the core tags and printing their own. The clean way is two PSR-14 events (both exist since TYPO3 v10), and since v13 you register the listeners with the One detail is easy to miss. Since v13.0 (Breaking-99807<\/a>) the canonical event is dispatched after the core has done its work, and it is also dispatched when canonical generation is disabled, for example because the page has I checked the class signatures in TYPO3 14.3. The canonical event got its current shape in v13.0 (Feature-99807<\/a>), so the code below is written for 13.4 and 14.3.<\/p>\n Example requirement: the site has an English language which editors are still filling. It is reachable, but hreflang should not advertise it yet. At the same time the organisation has a French site on a different system, and that one should be listed for the start page.<\/p>\n The A small warning: hardcoding page ids like I did above is fine for a blog example, but in a real project read them from site settings. Uids change when a tree is copied or content is imported again, and such constants are the first thing that breaks.<\/p>\n Second example: a list page has filter parameters like An explicit canonical which an editor sets in the page properties wins in the core before the event, and it will not contain the filter parameter, so this listener leaves it alone. If you need more page data, Nothing more. With Event listeners are small, so people often skip tests. But SEO tags break silently: nobody sees them in the browser. A functional test with typo3\/testing-framework<\/a> (version 9 supports both v13 and v14) renders a real page and checks the head. Here for the hreflang listener on the start page:<\/p>\n The TypoScript fixture only needs a minimal If this post helped you, I will be really happy. Feedbacks are the champion’s breakfast, so drop a comment if your project needed a different hreflang trick.<\/p>\n Two small event listeners for EXT:seo: one adjusts the hreflang list, one fixes the canonical URL. Registered with attributes only, and covered by a functional test.<\/p>\n","protected":false},"author":1,"featured_media":139,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17],"tags":[48,41,31,5,33,24],"class_list":["post-138","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-typo3","tag-psr-14-events","tag-seo","tag-testing","tag-typo3","tag-typo3-v13","tag-typo3-v14"],"yoast_head":"\n#[AsEventListener]<\/code> attribute. No hook arrays, no Services.yaml tags needed.<\/p>\nThe two events<\/h2>\n
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TYPO3CMSFrontendEventModifyHrefLangTagsEvent<\/code> is dispatched by the frontend RequestHandler<\/code>. The core listener HrefLangGenerator<\/code> from EXT:seo fills it, using the identifier typo3-seo\/hreflangGenerator<\/code>. Your listener gets getHrefLangs()<\/code>, setHrefLangs()<\/code>, addHrefLang()<\/code> and the request.<\/li>\nTYPO3CMSSeoEventModifyUrlForCanonicalTagEvent<\/code> is dispatched by CanonicalGenerator<\/code> just before the canonical tag is built. It has getUrl()<\/code>, setUrl()<\/code>, getRequest()<\/code>, getPage()<\/code> and getCanonicalGenerationDisabledException()<\/code>.<\/li>\n<\/ul>\nno_index<\/code> set. So getUrl()<\/code> can already contain a URL, or it can be empty for a good reason. Your listener must check this, otherwise you add a canonical to a page that should not have one.<\/p>\nStep 1: adjust the hreflang list<\/h2>\n
<?php\n\ndeclare(strict_types=1);\n\nnamespace VendorSitepackageEventListener;\n\nuse TYPO3CMSCoreAttributeAsEventListener;\nuse TYPO3CMSFrontendEventModifyHrefLangTagsEvent;\n\n#[AsEventListener(\n identifier: 'sitepackage\/hreflang',\n after: 'typo3-seo\/hreflangGenerator',\n)]\nfinal readonly class AdjustHrefLangTags\n{\n private const HIDDEN_LANGUAGES = ['en-GB'];\n\n public function __invoke(ModifyHrefLangTagsEvent $event): void\n {\n $hrefLangs = $event->getHrefLangs();\n foreach (self::HIDDEN_LANGUAGES as $code) {\n unset($hrefLangs[$code]);\n }\n\n $pageId = $event->getRequest()->getAttribute('frontend.page.information')?->getId();\n if ($pageId === 1) {\n $hrefLangs['fr-FR'] = 'https:\/\/fr.example.org\/';\n }\n\n \/\/ x-default only makes sense when there is still more than one language\n if (count($hrefLangs) < 3) {\n unset($hrefLangs['x-default']);\n }\n $event->setHrefLangs($hrefLangs);\n }\n}<\/code><\/pre>\nafter<\/code> argument is the important part. Without it, your listener may run before the core generator, and then there is nothing to remove yet. The core only prints the tags when the final array has more than one entry, so if you remove too much, the tags disappear completely. That is correct behaviour, not a bug.<\/p>\nStep 2: clean the canonical URL<\/h2>\n
?tx_events_list[category]=3<\/code>. The core fallback builds the canonical from the current page link including the cHash-relevant parameters, so every filtered view gets its own canonical. Say you want all filtered views to point to the plain list page instead.<\/p>\n<?php\n\ndeclare(strict_types=1);\n\nnamespace VendorSitepackageEventListener;\n\nuse TYPO3CMSCoreAttributeAsEventListener;\nuse TYPO3CMSCoreHttpUri;\nuse TYPO3CMSSeoEventModifyUrlForCanonicalTagEvent;\n\n#[AsEventListener(identifier: 'sitepackage\/canonical')]\nfinal readonly class StripFilterFromCanonical\n{\n public function __invoke(ModifyUrlForCanonicalTagEvent $event): void\n {\n \/\/ Disabled by TypoScript (disableCanonical) or by no_index: respect that\n if ($event->getCanonicalGenerationDisabledException() !== null) {\n return;\n }\n $url = $event->getUrl();\n if ($url === '' || !str_contains(urldecode($url), 'tx_events_list[')) {\n return;\n }\n $event->setUrl((string)(new Uri($url))->withQuery(''));\n }\n}<\/code><\/pre>\ngetPage()<\/code> gives you a TYPO3CMSCoreDomainPage<\/code> record object. Use has()<\/code> before get()<\/code> on it, because get()<\/code> throws an exception for a field that is not there.<\/p>\nStep 3: registration<\/h2>\n
autoconfigure: true<\/code> in your Configuration\/Services.yaml<\/code> (which every modern sitepackage has), the attribute registers the listener. You can check the result in the backend module System \u2192 Configuration \u2192 Event Listeners (PSR-14). After adding a new listener, flush the caches once: ddev typo3 cache:flush<\/code>.<\/p>\nStep 4: a functional test that reads the rendered tags<\/h2>\n
<?php\n\ndeclare(strict_types=1);\n\nnamespace VendorSitepackageTestsFunctional;\n\nuse PHPUnitFrameworkAttributesTest;\nuse TYPO3CMSCoreConfigurationSiteWriter;\nuse TYPO3TestingFrameworkCoreFunctionalFrameworkFrontendInternalRequest;\nuse TYPO3TestingFrameworkCoreFunctionalFunctionalTestCase;\n\nfinal class HrefLangTest extends FunctionalTestCase\n{\n protected array $coreExtensionsToLoad = ['seo'];\n protected array $testExtensionsToLoad = ['vendor\/sitepackage'];\n\n protected function setUp(): void\n {\n parent::setUp();\n \/\/ root page uid 1 and its English translation\n $this->importCSVDataSet(__DIR__ . '\/Fixtures\/pages.csv');\n $this->setUpFrontendRootPage(1, ['EXT:sitepackage\/Tests\/Functional\/Fixtures\/page.typoscript']);\n $this->get(SiteWriter::class)->write('test', [\n 'rootPageId' => 1,\n 'base' => 'https:\/\/www.example.org\/',\n 'languages' => [\n ['languageId' => 0, 'title' => 'Deutsch', 'locale' => 'de_DE.UTF-8', 'base' => '\/', 'hreflang' => 'de-DE'],\n ['languageId' => 1, 'title' => 'English', 'locale' => 'en_GB.UTF-8', 'base' => '\/en\/', 'hreflang' => 'en-GB'],\n ],\n ]);\n }\n\n #[Test]\n public function startPageListsPartnerSiteButNotHiddenLanguage(): void\n {\n $response = $this->executeFrontendSubRequest(new InternalRequest('https:\/\/www.example.org\/'));\n $html = (string)$response->getBody();\n\n self::assertStringContainsString('hreflang=\"fr-FR\" href=\"https:\/\/fr.example.org\/\"', $html);\n self::assertStringContainsString('hreflang=\"de-DE\"', $html);\n self::assertStringNotContainsString('hreflang=\"en-GB\"', $html);\n }\n}<\/code><\/pre>\npage = PAGE<\/code> with some output. Run it in DDEV, for example with ddev exec typo3DatabaseDriver=pdo_sqlite vendor\/bin\/phpunit -c Build\/phpunit\/FunctionalTests.xml<\/code>. For the canonical listener a request with filter parameters needs a valid cHash, so I find a plain unit test easier there: create the event with a URL, call the listener, compare getUrl()<\/code>.<\/p>\nWhat I learned<\/h2>\n
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after<\/code> for the hreflang listener, the core generator must run first.<\/li>\ngetCanonicalGenerationDisabledException()<\/code>; no_index<\/code> pages should stay without canonical.<\/li>\nFurther reading<\/h2>\n
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