Get Featured Image Outside Loop Not Working

Question

i have the following code to get the next and the previous article.

if(wp_get_post_parent_id($post->ID)){
    $pagelist = get_pages('post_parent='.wp_get_post_parent_id($post->ID));
    $pages = array();
    foreach ($pagelist as $page) {
    $pages[] += $page->ID;
    }

    $current = array_search($post->ID, $pages);
    $prevID = $pages[$current-1];
    $nextID = $pages[$current+1];


}

With the $nextID and $previID I am able to create a link like here:

<a title="<?php echo get_the_title( $prevID ); ?>" href="<?php echo get_permalink($prevID); ?>"><?php echo get_the_title( $prevID ); ?> &raquo;</a>

Now i want to also have the featured image of this $prevID and $nextID. I don't know why, but it does not work. I tried the following:

echo wp_get_attachment_url(get_post_thumbnail_id($prevID));

How can i do that? Even if i add the fix ID like 1253 instead of $prevID, it does not work. When i use $post->ID (of the current article, just to check), it works.

Any idea?

Answer 1

First you have to make sure the current post ID + 1 and Current post ID - 1 is exactly the post ID of the next and previous posts.

if it is correct then you can use

<img src="<?php $image = wp_get_attachment_image_src( get_post_thumbnail_id($prevID), 'full'); echo $image[0];?>" />

and

<img src="<?php $image = wp_get_attachment_image_src( get_post_thumbnail_id($nextID), 'full'); echo $image[0];?>" />

The wp_get_attachment_image_src returns an array with image url as the first element of the array

Answer 2

Are you sure $prevID even contains an ID? Try to echo it out first.

If so, the following code will output the full <img src="" /> tag to display the image. The second parameter is the size you want.

echo get_the_post_thumbnail( $prevID, 'post-thumbnail' );

get_the_post_thumbnail