Adds custom callback for Dynamic Field widget from JetEngine to output related items list with thumbnails

advanced-related-items-list.php

<?php
add_filter( 'jet-engine/listings/allowed-callbacks', function( $callbacks ) {
	$callbacks['jet_advanced_rel_list'] = 'Advanced realtions list';
	return $callbacks;
} );

function jet_advanced_rel_list( $items = [] ) {
	
	if ( empty( $items ) ) {
		return;
	}

	$res = '';

	foreach ( $items as $item_id ) {
		
		/**
		 * The data in example is get for posts.
		 * You can replace it with data appropriate for your related items - users, terms etc.
		 */
		$title = get_the_title( $item_id );
		$thumb = get_the_post_thumbnail( $item_id, [ 150, 150 ], [ 'alt' => $title, 'class' => 'jet-rel-list__thumb' ] );
		$link  = get_permalink( $item_id );

		$res .= sprintf( '
			<div class="jet-rel-list__item">
				<a href="%3$s" class="jet-rel-list__link">
					%2$s
					<div class="jet-rel-list__title">%1$s</div>
				</a>
			</div>',
			$title,
			$thumb,
			$link
		);
	}

	return sprintf( '<div class="jet-rel-list">%s</div>', $res );

}