issue with custom post type feed

Question

Custom Post type feed url showing the main feed's content.

Details: i have some custom post type on my site. I added them to main feed using this snippet

function mycustomfeed_cpt_feed( $query ) {

  // Add to my custom-type post type
  $types = array('post','blood-blog');

        if ( $query->is_feed() )
            $query->set( 'post_type', $types ); 
        return $query;
}
add_filter( 'pre_get_posts', 'mycustomfeed_cpt_feed' );

Here is how I registered the post type

/*Register Blood Blog*/
function mcp_blood_blog() {
    $labels = array(
        'name'               => _x( 'Blood Blog', 'post type general name' ),
        'singular_name'      => _x( 'Blood Blog', 'post type singular name' ),
        'add_new'            => _x( 'Add New', 'Blood Blog' ),
        'add_new_item'       => __( 'Add New Blog' ),
        'edit_item'          => __( 'Edit' ),
        'new_item'           => __( 'New Blood Blog' ),
        'all_items'          => __( 'Blood Blog' ),
        'view_item'          => __( 'View Blog' ),
        'search_items'       => __( 'Search Blog' ),
        'not_found'          => __( 'No Blog Found' ),
        'not_found_in_trash' => __( 'No Blog Found Trash' ),
        'parent_item_colon'  => '',
        'menu_name'          => 'Blood Blog'
    );
    $args = array(
        'labels'        => $labels,
        'description'   => 'Insert A Blood Blog',
        'public'        => true,
        'menu_position' => 5,
        'menu_icon'     => 'dashicons-heart',
        'supports'      => array( 'title', 'editor', 'thumbnail', 'excerpt', 'comments', 'author' ),
        'has_archive'   => true,
        'hierarchical'  => false,
        'rewrite'       => array('slug' => 'blood/blog','with_front' => true,'feeds' => true,),
        'query_var'     => true,
        'publicly_queryable'    => true,
        'public'                => true,
        'show_in_admin_bar' => true,
        'show_in_nav_menus' => false,
        'capability_type' => 'post',
        '_edit_link' => 'post.php?post=%d' ,
    );
    register_post_type( 'blood-blog', $args );
}
add_action( 'init', 'mcp_blood_blog' );
/*End Blood Blog*/

The problem is when i try to get the feed from custom post type like this one:

http://www.mediwaretesting.com/blood/blog/feed/

it returns the main feed content that already in

http://www.mediwaretesting.com/feed/

note: "blood/blog" in post type slug.

Answer 1

Note that $query->is_feed() is true for both feeds, so you're changing both of them with the pre_get_posts hook.

I skimmed quickly through the WP_Query object for those feeds and if you want to combine these two post types, only for the main feed example.tld/feed/, you could try:

add_filter( 'pre_get_posts', function( \WP_Query $q )
{
    if ( 
            $q->is_feed() 
         && ! $q->is_archive() 
         && ! $q->is_singular() 
         && ! $q->is_comment_feed() 
    )
        $q->set( 'post_type', [ 'post', 'blood-blog' ] );       
} );

I might be missing some checks, so you might want to double check it.

ps: it would be nice to have is_feed_home() or is_main_feed() here ;-)