Translated POSTS urls in WPML WordPress website with a "Page for Posts" as POST-URL-base

translated-page-for-posts-post-url-base.php

<?php

/**
 * Notes on the following section
 *
 * Correct set-up is:
 *
 * Set your page-for-posts to a certain WordPress Posts, for example /nl/nieuws/
 * Set your permalink structure to the same; /nieuws/%postname%/
 *
 * WordPress will generate links for "some-article-in-german" as /de/nieuws/some-article-in-german
 * Code below will rewrite /(any-language)/(any-translation-of-/nieuws)/ to /the-language/the-translated-page/the-post/,
 * like /de/neuigkeiten/some-article-in-german
 *
 * If you have problems;
 *
 * Re-save permalinks
 *
 * If you changed the languages in your site;
 *
 * Re-save permalinks
 *
 * If you change the "Page for Posts" for your site;
 *
 * Re-save permalinks
 *
 */

add_filter( 'post_link', function ( $permalink, $post, $leavename ) {
	static $shortcircuit, $languages, $patch;
	if ( ! $shortcircuit ) {
		if ( 'post' === get_post_type( $post ) ) {
			if ( ! $languages ) {
				$languages = apply_filters( 'wpml_active_languages', array(), 'skip_missing=0' );
				$languages = array_keys( $languages );
				$languages = implode( '|', $languages );
				$languages = "($languages)";
			}
			if ( ! $patch ) {
				$patch = get_option( 'page_for_posts_patch' );
				// do nothing if there is no patch available
				if (!$patch) {
					return $permalink;
				}
			}

			$post_page = get_option( 'page_for_posts' );
			$post_page = apply_filters( 'wpml_object_id', $post_page, 'post', true );

			$shortcircuit = true;
			$link         = get_permalink( $post_page );
			$shortcircuit = false;

			// this is an elaborate replacement to make absolutely sure this changes the FIRST and ONLY the first occurrence
			$permalink = preg_replace( '/\/' . $languages . '\/' . $patch . '\//', '/' . ICL_LANGUAGE_CODE . '/%page_for_posts%/', $permalink, 1 );
			$permalink = explode( '/' . ICL_LANGUAGE_CODE . '/%page_for_posts%/', $permalink, 2 );
			$permalink = $link . $permalink[1];
		}
	}

	return $permalink;
}, PHP_INT_MAX, 3 );


add_filter( 'term_link', function( $permalink, $term, $taxonomy ) {
	static $shortcircuit, $languages, $patch;
	if ( ! $shortcircuit ) {
		$shortcircuit = true;

		if ( ! $languages ) {
			$languages = apply_filters( 'wpml_active_languages', array(), 'skip_missing=0' );
			$languages = array_keys( $languages );
			$languages = implode( '|', $languages );
			$languages = "($languages)";
		}
		if ( ! $patch ) {
			$patch = get_option( 'page_for_posts_patch' );
			// do nothing if there is no patch available
			if (!$patch) {
				return $permalink;
			}
		}

		$post_page = get_option( 'page_for_posts' );
		$post_page = apply_filters( 'wpml_object_id', $post_page, 'post', true );

		$link         = get_permalink( $post_page );

		// this is an elaborate replacement to make absolutely sure this changes the FIRST and ONLY the first occurrence
		$permalink = preg_replace( '/\/' . $languages . '\/' . $patch . '\//', '/' . ICL_LANGUAGE_CODE . '/%page_for_posts%/', $permalink, 1 );
		$permalink = explode( '/' . ICL_LANGUAGE_CODE . '/%page_for_posts%/', $permalink, 2 );
		$permalink = $link . $permalink[1];

		$shortcircuit = false;
	}

	return $permalink;
}, PHP_INT_MAX, 3 );


add_filter( 'icl_ls_languages', function ( $languages ) {
	global $sitepress;

	$current_language = $sitepress->get_current_language();
	$post_page = get_option( 'page_for_posts' );
	$patch = get_option( 'page_for_posts_patch' );
	
	foreach ( $languages as $language_code => &$language ) {
		if (preg_match( '@/' . $patch . '/@', $language['url'] )) {
			$post_page = apply_filters( 'wpml_object_id', $post_page, 'post', true, $language['code'] );
			$sitepress->switch_lang($language['code']);
			$link         = get_permalink( $post_page );

			$language['url'] = preg_replace( '@/' . $patch . '/@', '/****/', $language['url'] );
			$language['url'] = explode('****/', $language['url']);
			$language['url'] = $link . $language['url'][1];
		}
	}
	$sitepress->switch_lang($current_language);

	return $languages;
} );


/**
 * Purpose of this filter:
 *
 * 1. rewrite the rewrite rules.
 *
 * WordPress generates rules based on the Permalink structure.
 * Example: /nieuws/%postname%/
 * Will generate rules starting with 'nieuws/' but then will fail to detect urls that should be translated;
 * /de/neuigkeiten/ for example.
 * The code below makes the rule '(?:nieuws|neuigkeiten|news|....) based on all translations of the "Page for Posts".
 * This fix is called the "patch", and will be stored for later use
 *
 * 2. Store the patch so the code-block above can use it.
 *
 * Because of this piece of caching;
 *
 * If you have problems;
 *
 * Re-save permalinks
 *
 * If you changed the languages in your site;
 *
 * Re-save permalinks
 *
 * If you change the "Page for Posts" for your site;
 *
 * Re-save permalinks
 *
 */

add_filter('rewrite_rules_array', function($rules) {
	$patch = false;
	$post_page = get_option( 'page_for_posts' );

	// do nothing if we don't have this setting.
	if (!$post_page) {
		update_option('page_for_posts_patch', false);
		return $rules;
	}

	$keys = array_keys($rules);
	$values = array_values($rules);

	$has_one = false;

	foreach ($keys as &$key) {
		if ( ! $patch ) {
			$languages = apply_filters( 'wpml_active_languages', array(), 'skip_missing=0' );
			foreach ( $languages as $language_code => $data ) {
				$id                                                 = apply_filters( 'wpml_object_id', $post_page, 'post', true, $language_code );
				$all_permalinks_for_all_languages[ $language_code ] = explode('/'. $language_code .'/', get_permalink( $id ), 2);
				$all_permalinks_for_all_languages[ $language_code ] = trim($all_permalinks_for_all_languages[ $language_code ][1], '/');
			}

			$patch = '(?:'. implode('|', $all_permalinks_for_all_languages) .')';
			update_option('page_for_posts_patch', $patch);
		}

		$_key = preg_replace('/^'. $patch .'\//', $patch.'/', $key);
		if ($key != $_key) {
			$has_one = true;
		}
		$key = $_key;
	}

	if (!$has_one) {
		update_option('page_for_posts_patch', false);
		return $rules;
	}

	$rules = array_combine($keys, $values);

	return $rules;
});

xxDocumentation.md

With WPML you can localize the "page for posts", this will localize the post-URL-base according to the actual page URL.

With WPML you can localize the slug of your CPT single, but not your CPT archive, if you give it a different content. You can fix the translations with https://gist.github.com/rmpel/d9989da79956fb0eafe81e49331b84b6 .

While this will fix all URLs on the front-end, you will still need to fix the Sitemap links, in case you use Yoast SEO (Basic or Premium), or SEO by Rank Math. You van do this with https://gist.github.com/rmpel/b00997f2504c39c718028dfa7e79b87c .