Polylang and Related Posts plugin

Hi!

I don’t use Jetpack myself but I aim to make Polylang compatible with this plugin. Here is a small plugin which may help:

<?php

/*
Plugin name: Polylang Jetpack Related Posts
*/

if ( function_exists( 'pll_get_post_language' ) )
add_filter( 'jetpack_relatedposts_filter_has_terms', 'pll_jetpack_relatedposts_filter_has_terms', 10, 2 );

function pll_jetpack_relatedposts_filter_has_terms( $terms, $post_id ) {
	$term_id = pll_get_post_language( $post_id, 'term_id' );
	$terms[] = get_term( $term_id, 'language' );
	return $terms;
}

Once it is activated, there should be a way in Jetpack option to reindex the related posts. According to the documentation, it is located under Jetpack → Debug (link in the footer) → Reindex.

Please tell me if it solves your issue. If so, I will include the code in Polylang.

EDIT: I edited the code as there was a bug in the initial version

It seems no related posts appear at all now.
Note that my site is part of a WordPress multisite installation.
The url is https://www.reflektis.com/blog-en for the blog articles that I want to show related posts.

I ended up to make my own tests and I confirm the issue. Please keep the plugin active. I am in contact with the Jetpack team to try to understand what’s wrong.

I made a new version that seems to work:

<?php

/*
Plugin name: Polylang Jetpack Related Posts
*/

if ( function_exists( 'pll_get_post_language' ) )
add_filter( 'jetpack_relatedposts_filter_filters', 'pll_jetpack_relatedposts_filter_filters', 10, 2 );

function pll_jetpack_relatedposts_filter_filters( $filters, $post_id ) {
	$slug = sanitize_title( pll_get_post_language( $post_id, 'name' ) );
	$filters[] = array( 'term' => array('taxonomy.language.slug' =>  $slug ) );
	return $filters;
}

You have to reindex your posts. if debug->reindex does not work, try to change the status of your posts from published to draft then published again (using the bulk action).