Theme Function Filter disables Admin Dashboard Post Filter

[antonv]

I have following filter in my theme functions.php to exclude post from an Archive Widget:

function exclude_category($query) {
if ( $query->is_archive ) {
$query->set('cat', '-26,-1,-57,-58');
}
return $query;
} 
add_filter('pre_get_posts', 'exclude_category');

However, this disables the filter by category on the Posts-page (../wp-admin/edit.php). Removing above code from theme functions.php the Post-page filter works as it is intended to do. This is new as the Posts-page filter used to work on an earlier version of WP with above code in the theme functions.php.

Surely theme filters should not take precedence over the wp-admin pages.

[SergeyBiryukov]

'pre_get_posts' ​runs in the admin too. You should add an is_admin() check to your function.

It's also a good idea to add a $query->is_main_query() check.