WP_Query with custom post type ID

Question

This code isn't echoing out anything, even though I'm 100% positive $mixtape_id is set to an integer which corresponds to one of the posts within the 'mixtapes' custom post type

$query = new WP_Query(array(
  'post_type'      => 'mixtapes',
  'p'              => (int)$mixtape_id,
  'posts_per_page' => -1,
  'orderby'        => 'meta_value_num',
  'meta_key'       => 'track_number'
));

while ( $query->have_posts() ) : $query->the_post(); ?>

<track>
    <location>track1.mp3</location>
    <creator>Artist name</creator>
    <title>Track 1</title>
</track>

<?php endwhile; ?>

Answer 1

I fixed it by doing it a different way

$query = new WP_Query(array(
  'post_type'      => 'tracks',
  'posts_per_page' => -1,
  'orderby'        => 'meta_value_num',
  'meta_key'       => 'track_number',
  'meta_query'     => array(
    array(
        'meta_key'   => 'mixtape',
        'meta_value' => (string)$mixtape_id
    )
  )
));