How to exclude posts from category posts count

Question

I have a custom loop to display posts based on a custom field. My problem is that if i have 2 posts and exclude 1 from the loop the category posts count (categories list widget with show count enable) still remains 2.

Answer 1

Assuming you have a list containing the post IDs you want to exclude, you could start with something like (PHP 7.3):

function exclude_posts_from_category( array $cat_args ): array {
    $exclude = array(); // TODO Add post IDs to exclude.
    $cat_args['exclude'] = $exclude;
    return $cat_args;
}
add_filter( 'widget_categories_args', 'exclude_posts_from_category', 10, 1 );

You can read about the widget_categories_args filter here. Additionally, you can alter the $cat_args array using a combination of arguments that can be found in the documentation of the wp_list_categories() function.

I did not fully test this code, so let me know in case you're having any trouble.

Answer 2

If you want to exclude posts from all queries, if you are not an "admin", and excluding the "single" query - so you can open the post, you can use this:

add_action('pre_get_posts', 'exclude_posts_from_all_queries');
function exclude_posts_from_all_queries($query) {
  $exclude_posts = array('9');
  if ( !is_admin() && !is_single() ) {
    $query->set('post__not_in', $exclude_posts);
  }
}

Just add the Posts ID number to $exclude_posts array.

Hope that it helps,
Cheers