Get a custom field of all posts on current blog page

Question

I am trying to get a custom field value from all posts listed on current blog paginated page. Not sure if it's clear, let me explain it more.

On blog index page (or on second page of pagination) I have 10 posts. And each post have a value for custom field my-field. So I want to list posts as it is but outside the post list (lets say in footer.php) I want to also list all the values of custom field my-field belonging to current posts.

Not sure exactly how it can be done.

EDIT

To simplify (for understanding), I want to echo posts IDs of all listed posts in footer.php.

Answer 1

You could just rewind the query to loop through again:

<?php rewind_posts(); ?>

<?php while ( have_posts() ) : the_post(); ?>
    <p>Post Number: <?php the_ID(); ?></p>
<?php endwhile; ?>

THE LOOP

Answer 2

If I understand you correctly, you just need to get all the ID's. The $wp_query global is available as the main query has already executed, so can just access the $posts property and from there get your post ID's. Something like this will do

global $wp_query;
$posts = $wp_query->posts;
foreach ( $posts as $post ) {
    echo $post->ID;
}

If you need an array of ID's, do the following

global $wp_query;
$posts = $wp_query->posts;

$ids = [];
foreach ( $posts as $post ) {
    $ids[] = $post->ID;
}

?><pre><?php var_dump($ids); ?></pre><?php

All your post ID's will be held in the $ids variable