Filter on one post type with taxonimy and get other post type

Question

I would like to fetch my posts of type 'news', 'videos', 'webinars', 'whitepapers', 'testimonials', and 'landing-pages' and apply a "filter" to only get the landing-pages type with the taxonomy 'landing_pages_display_home' having 'displayed-on-home-page' as terms and 'slug' as the field and my other post type.

This is my current query, it does return the landing-pages with the defined taxonomy and terms, but I do not get the other post types.

$args = array(
    'posts_per_page' => 6,
    'post_status'    => 'publish',
    'order'          => 'DESC',
    'post_type'      => array(
                                'news',
                                'videos',
                                'webinars',
                                'whitepapers',
                                'testimonials',
                                'landing-pages'
                            ),
    'tax_query' => array(
        array(
            'taxonomy' => 'landing_pages_display_home',
            'field'    => 'slug',
            'terms'    => 'displayed-on-home-page',
        ),
    ),
);

$resources = new WP_Query($args);

My question is, how can I get the posts of type 'news', 'videos', 'webinars', 'whitepapers', 'testimonials' and the 'landing-pages' posts having 'displayed-on-home-page' as terms and 'slug' as the field?

There is my taxonomy :

register_taxonomy(
    'landing_pages_display_home',
    array('landing-pages'), /* if you change the name of register_post_type( 'custom_type', then you have to change this */
    array(
        'hierarchical' => true,     /* if this is true, it acts like categories */
        'labels' => array(
            'name'              => __( 'Categories', 'domain_name' ), /* name of the custom taxonomy */
            'singular_name'     => __( 'Categories', 'domain_name' ), /* single taxonomy name */
            'search_items'      => __( 'Search Categories', 'domain_name' ), /* search title for taxomony */
            'all_items'         => __( 'All Categories', 'domain_name' ), /* all title for taxonomies */
            'edit_item'         => __( 'Edit Categories', 'domain_name' ), /* edit custom taxonomy title */
            'add_new_item'      => __( 'Create new Categorie', 'domain_name' ), /* add new title for taxonomy */
            'parent_item'       => __('Parent Categories', 'domain_name'), // parent title for taxonomy
            'parent_item_colon' => __('Parent Categories:', 'domain_name'), // parent taxonomy title
            'update_item'       => __('Update Categories', 'domain_name'), // update title for taxonomy
        ),
        'show_admin_column' => true,
        'show_ui' => true,
        'query_var' => true,
        'show_in_rest' => true, // Needed for tax to appear in Gutenberg editor.
        'rewrite' => array('slug' => 'landing_pages_display_home'),
    )
);

Let me know if you want more details. I'm pettry new with wordpress, so thanks for any help that you give me !

EDIT :

I managed to do something like this :

$args_landing_pages = array(
                        'posts_per_page' => 6,
                        'post_status'    => 'publish',
                        'order'          => 'DESC',
                        'post_type'      => 'landing-pages',
                        'tax_query' => array(
                            array(
                                'taxonomy' => 'landing_pages_display_home',
                                'field'    => 'slug',
                                'terms'    => 'displayed-on-home-page',
                            ),
                        ),
                    );
                  
$query_landing_pages = new WP_Query($args_landing_pages);
$landing_page_ids = wp_list_pluck($query_landing_pages->posts, 'ID');
                  
$args_others = array(
                        'posts_per_page' => 6,
                        'post_type'      => array(
                            'news',
                            'videos',
                            'webinars',
                            'whitepapers',
                            'testimonials'
                        ),
                        'order'          => 'DESC',
                        'post_status'    => 'publish',
                    );
                  
$query_others = new WP_Query($args_others);
$other_post_ids = wp_list_pluck($query_others->posts, 'ID');
                    
// Combine IDs
$combined_post_ids = array_merge($landing_page_ids, $other_post_ids);
                    
// Construct the final request THAT NOT REQUEST to the db, so we can preserve performences and compatibility with wordpress functions
                    $args_combined = array(
                        'post_type' => 'any',
                        'post_status' => 'publish',
                        'posts_per_page' => 6,
                        'post__in' => $combined_post_ids,
                        'orderby' => 'post__in' 
);
                  
$resources = new WP_Query($args_combined);

But it needs 2 requests to work so that's not performance friendly... So I still need help with this :(

Answer 1

tax_query with an 'OR' relation. This means that the query will fetch posts that meet either condition: they are 'landing-pages' with the specified taxonomy terms, or they are any of the other specified post types without additional taxonomy constraints.

$args = array(
'posts_per_page' => 6,
'post_status'    => 'publish',
'order'          => 'DESC',
'post_type' => array('news', 'videos', 'webinars', 'whitepapers', 'testimonials', 'landing-pages'), // Include all your target post types
'tax_query' => array(
    'relation' => 'OR', // Important for combining different post type conditions
    array(
        'taxonomy' => 'landing_pages_display_home',
        'field'    => 'slug',
        'terms'    => 'displayed-on-home-page',
        // Ensure only 'landing-pages' post type is affected by this taxonomy query
        'include_children' => false,
        'operator'  => 'IN'
    ),
    array(
        'operator' => 'EXISTS', // This allows posts of other types without further conditions
    )
  )
);

$resources = new WP_Query($args);