Displaying custom post type on category pages but not on blog listings

Question

I think this is a fairly simple issue but I haven't got my head around it.

Question: how do I get my custom posts to show only on the category archives, but not in the blog post listing page?

Background: I have a custom post type "video", with has_archive true and 'taxonomies' => array('category', 'post_tag') - I want to use standard categories with this custom post type.

I have successfully got my category pages to display by setting post_type and using the hook pre_get_posts as follows:

function my_query_post_type($query) {
    if ( is_home() && false == $query->query_vars['suppress_filters'] )
        $query->set( 'post_type', array( 'post', 'video', 'attachment' ) );
    return $query;
}
add_filter('pre_get_posts', 'my_query_post_type');

If I don't use pre_get_posts, then my videos don't show - as expected.

However, now my blog post listing page shows the custom posts - as expected because I've changed the post_type in query.

Question: how do I get my custom posts to show only on the category archives, but not in the blog post listing page?

Answer 1

This may be overly simplistic, but have you tried changing is_home() to is_category(), in this line:

if ( is_home() && false == $query->query_vars['suppress_filters'] )

i.e. change it to this:

if ( is_category() && false == $query->query_vars['suppress_filters'] )

Worth a shot, anyway...

Answer 2

This is not easy to explain, but if someone else sees the issue they will be thankful, as I didn't catch this bug until months later when adding some other customization. I found out that !is_admin() was needed to prevent triggering this query in the administration page. An error was occurring when I filtered twice in a row on Category to toggle between posts from two different categories. The error would not occur when I only filtered once. It would always come up on the second attempt to filter. This toggling between categories was important for me as I added a couple extra quick edit fields to dealing with sorting of posts.

So I added !is_admin() which eliminated the issue.

is_category() && (!is_admin()) && false == $query->query_vars['suppress_filters'] 

my URL was the following ugly thing after the second time of trying to filter on a category for the second time:

edit.php?post_status=all&post_type=Array&_wpnonce=09d0e899fa&_wp_http_referer=%2Fironglasslighting.org%2Fwp-admin%2Fedit.php%3Fs%26post_status%3Dall%26post_type%3Dproduct%26action%3D-1%26m%3D201112%26cat%3D31%26paged%3D1%26mode%3Dlist%26action2%3D-1&action=-1&m=201112&cat=27&paged=1&mode=list&action2=-1