How to query posts with featured images

Question

I basically want to use WP_Query to select 3 latest posts which have featured images and this is the only way I can think of.

regards

edit

tried

$query = new WP_Query( array( "post_type" => 'case-study', 'meta_key' => '_thumbnail_id', "posts_per_page" => '10', 'orderby' => 'menu_order' ) );

which doesn't work

I'm trying to add a custom field to add a hidden custom field to a post when there is a featured image attached (either true or false).

I've tried hooking into updated_post_meta, update_post_meta, wp_insert_post but I cant seem to match the $meta_key to "_thumbnail_id".

edit

function get_latest_with_featured_image( $args = array() ) {
    $args = array_merge( array( "post_type" => 'post', "meta_key" => "_thumbnail_id", "posts_per_page" => '10', 'orderby' => 'menu_order' ), $args );
    $query = new WP_Query( $args );
    return $query->posts;
}

$posts = get_latest_with_featured_image( array(  "post_type" => "case-studies",  "posts_per_page" => 10 ) );

Answer 1

You've provided the answer to your own question, query for meta key _thumbnail_id to get posts with a featured image:

$args = array(
    'meta_key' => '_thumbnail_id',
    'posts_per_page' => 3
);
$latest_with_thumbnails = new WP_Query( $args );