如何处理帖子并在输出之前将其导出为CSV？

Question

I am trying to export as CSV a list of custom type posts directly from Wordpress' dashboard (edit.php). This is my code so far:

add_filter('pre_get_posts', 'yri_export_csv');

function yri_export_csv($query) {
    if(is_admin() && $query->get('post_type') == 'kohde' && isset($_GET['export_csv'])) {
        $kunta = $query->get('kunta');
        $osasto = $query->get('osasto');
        $time = time();

        $args = $query->query;
        $posts = get_posts($args);

        header('Content-type: application/csv');
        header("Content-Disposition: attachment; filename=kohteet_{$kunta}_{$osasto}_{$time}.csv");

        foreach ($posts as $post) {
            // Do CSV stuff here
        }

        die();
    }
}

The problem is that when I query the posts using get_posts or new WP_Query Wordpress for some reason redirects me to the frontend, to a 404 page. Why does it do that?

Answer 1

This solved it:

...
if(is_main_query() && is_admin() && $query->get('post_type') == 'kohde' && isset($_GET['export_csv'])) {
...

I'm not exactly sure why. There seems to be some kind of redirecting mechanic in Wordpress here and I don't exactly understand how it works. However, testing for main query, is_main_query() , was the missing piece.