Hide comments from admin comments.php that user can't edit or manage

Question

I am running into a problem in that I have users that can edit comments, but only those placed onto their own posts. Which is what I want. Unfortunately the edit-comments.php page shows all comments. Is there a way to hide/remove the comments that the user can't manage anyway?

I tried:

function my_plugin_get_comment_list_by_user($clauses) {
if (is_admin()) {
    global $user_ID, $wpdb;
    $clauses['join'] = ", wp_posts";
    $clauses['where'] .= " AND wp_posts.post_author = ".$user_ID." AND wp_comments.comment_post_ID = wp_posts.ID";
}
return $clauses;
}

if(!current_user_can('edit_others_posts')) {
add_filter('comments_clauses', 'my_plugin_get_comment_list_by_user');
}

But this has no effect

Answer 1

I found another piece of code on the internet which I have modified to work.

add_filter('the_comments', 'edit_comments_filter_comments');

function edit_comments_filter_comments($comments){
    global $pagenow;

    $currentuserid = get_current_user_id();

    if($pagenow == 'edit-comments.php' && !current_user_can('edit_others_posts')){
        foreach($comments as $i => $comment){
            $the_post = get_post($comment->comment_post_ID);
            if($comment->user_id != $currentuserid  && $the_post->post_author != $currentuserid)
                unset($comments[$i]);
        }
    }
    return $comments;
}

As I understand it, this takes the comments pulled in by the query and checks them before displaying them.

Answer 2

Instead of modifying raw SQL it's easier to add a parameter to the comment query combined with a condition in pre_get_comments:

https://developer.wordpress.org/reference/hooks/pre_get_comments/

E.g. this filter modifies the comment query in the admin area to only show comments on posts that belong to you:

add_action( 'pre_get_comments', 'only_your_posts_comments_in_admin' );
function only_your_posts_comments_in_admin( WP_Comment_Query $query ) : void {
    if ( ! is_admin() ) {
        return; // we only want to change admin screens
    }

    // limit to just the comments I made:
    $query->set( 'user_id', get_current_user_id() );
}

You can then modify that function to check if the user can/can't modify other peoples posts via current_user_can.