Displaying custom post type category archive page

Question

I have created custom post type:

function create_posttype() {

register_post_type( 'builds',
// CPT Options
    array(
        'labels' => array(
            'name' => __( 'Builds' ),
            'singular_name' => __( 'Build' )
        ),
                'taxonomies' => array('category', 'post_tag'),
        'public' => true,
        'has_archive' => true,
        'rewrite' => array('slug' => 'builds'),
                    'supports' => array('thumbnail', 'title', 'excerpt',      'revisions', 'comments', 'author')
    )
);}

       // Hooking up our function to theme setup
     add_action( 'init', 'create_posttype' );`

Custom post type is working without any problems but I cannot get one thing to work:

So basic idea is that there is custom post type "Builds" and I am using post categories (not custom taxonomies, because in my situation it's not viable option) to separate these Builds - for example Melee builds, Ranged builds, Spell Builds etc. I'd like to make archive for each category of custom post type, for example display all the Melee builds. For that I am using category templates, for example category-melee.php based on category slug which is working fine, but it doesn't show any posts from custom post type there - only regular posts with given category. What to do in this situation? Should I try to find and modify wp_query somewhere in theme to include "Builds" (because I've tried that and without success) or are there some other workarounds? Thank you.

Answer 1

Managed to solve the problem by adding this snippet to my functions.php

add_action('pre_get_posts', function($query) {
if ( ! is_admin() && $query->is_main_query() ) {

    if ( is_archive() || is_category() ) {
        $query->set( 'post_type', 'builds' );
    }


}
});

Answer 2

function namespace_add_custom_types( $query ) 
{
   if( is_category() || is_tag() && empty( $query->query_vars['suppress_filters'] ) ) 
   {
      $query->set( 'post_type', array(
      'post', 'nav_menu_item', 'your-custom-post-type-here'
       ));
      return $query;
   }
}
add_filter( 'pre_get_posts', 'namespace_add_custom_types' );