John Davidson

Message:

I've got a template part in a custom theme and all I'm doing is a WordPress query and in the loop displaying the post thumbnail.

<?php $posts = $args['posts'];



$q_args = [

  'post_type' => 'post',

  'post__in' => $posts

];



$posts_query = new WP_Query($q_args);

if( $posts_query->have_posts() ) { ?>

  <div class="posts-grid">

    <?php while( $posts_query->have_posts() ) {

      $posts_query->the_post();

      $post_id = get_the_ID(); ?>

      <div class="post-container">

        <a class="post" href="<?php the_permalink(); ?>">

          <div class="post-content">

            <?= get_the_post_thumbnail($post_id, 'blog-thumbnail') ?>

            <?= get_the_date('d M Y'); ?>

            <?php the_title('<h3>', '</h3>'); ?>

          </div>

        </a>

      </div>

    <?php }

    wp_reset_postdata(); ?>

  </div>

<?php } ?>

When I go to view the page the loop shows, and everything pulls through correctly, however I get an alert before the thumbnail image

Warning: Attempt to read property "ID" on int in /wp-includes/post-thumbnail-template.php on line 116

Looking at line 116 in that file it's part of the update_post_thumbnail_cache function

function update_post_thumbnail_cache( $wp_query = null ) {

    if ( ! $wp_query ) {

        $wp_query = $GLOBALS['wp_query'];

    }



    if ( $wp_query->thumbnails_cached ) {

        return;

    }



    $thumb_ids = array();



    foreach ( $wp_query->posts as $post ) {

        $id = get_post_thumbnail_id( $post->ID );

        if ( $id ) {

            $thumb_ids[] = $id;

        }

    }



    if ( ! empty( $thumb_ids ) ) {

        _prime_post_caches( $thumb_ids, false, true );

    }



    $wp_query->thumbnails_cached = true;

}

I thought at first it was that because I was passing the post ID to get_the_post_thumbnail, but if I change that to passing the post object I still get the same warning. Can anyone share with me what I've done to cause this warning?

Thanks!

---

My Answer:
It looks like the issue is with the way you are passing the post ID to the get_the_post_thumbnail function. Instead of passing the post ID directly, you should pass the post object itself.

Try updating this line:
php



to this:
php



By passing the post object to the get_the_post_thumbnail function, you should be able to resolve the warning you are seeing.