WordPress Infinite Loop on Single Post - php

Question

I've taken some code from https://gist.github.com/banago/5603826 so that I am able to do previous/next posts for a specific post on my WordPress site which is a custom post type of 'product'.
<?php
if( get_adjacent_post(false, '', true) ) {
previous_post_link('%link', '← Previous Post');
} else {
$first = new WP_Query('post_type=products&posts_per_page=1&order=DESC'); $first->the_post();
echo '← Previous Post';
wp_reset_query();
};
if( get_adjacent_post(false, '', false) ) {
next_post_link('%link', 'Next Post →');
} else {
$last = new WP_Query('post_type=products&posts_per_page=1&order=ASC'); $last->the_post();
echo 'Next Post →';
wp_reset_query();
};
?>
However it doesn't actually infinitely loop, if it's on the first or last post, the link outputs the page it's already on. An example can be found here - http://s860623395.websitehome.co.uk/products/bespoke-build/
Any solutions to this? Thanks!

Answer 1

Was just working on this myself the other day for a portfolio.
Here is what worked for me (adjusted for your product loop)
It should show a single next product indefinitely (infinite loop)
if( get_adjacent_post(false, '', true) ) {
$previous_link_url = get_permalink( get_previous_post() );
echo '← Next Product';
} else {
$first = new WP_Query('post_type=product&posts_per_page=1&order=DESC');
$first->the_post();
echo 'Next Product →';
wp_reset_query();
};
Just a note, next post is actually the previous post, It's a confusing thing, but when you view the latest post, be it portfolio, product or whatever, the next one is actually the one before, otherwise the next post after the most recent published post would then be the oldest one. This seems to be how most have done it within an infinite loop.

Answer 2

Like you, I tried many variations, none of which really worked, but this one did. Currently I'm using it in the Genesis framework for a portfolio CPT with a background image.
Here is the full working code below taken from a child theme:
add_action( 'genesis_after_content_sidebar_wrap', 'go_prev_next_post_nav_cpt', 999 );
/**
* Enable next link in portfolio.
*
* #since 1.0.0
*/
function go_prev_next_post_nav_cpt() {
echo '<div class="adjacent-entry-pagination">';
echo '<div class="wrap">';
if( get_adjacent_post(false, '', true) ) {
$prevThumb = get_the_post_thumbnail_url( get_previous_post(), 'full' );
$previous_link_url = get_permalink( get_previous_post() );
$prevTitle = get_the_title( get_previous_post() );
echo '<a class="post-link bg-image bg-overlay" href="' . $previous_link_url . '" style="background-image:url(' . $prevThumb . ')"><div class="next-description"><p class="mast">Next project</p><h3 class="display-2">' . $prevTitle . '</h3></div></a>';
} else {
$first = new WP_Query('post_type=portfolio&posts_per_page=1&order=DESC');
$first->the_post();
$bg_image = get_the_post_thumbnail_url();
echo '<a class="post-link bg-image bg-overlay" href="' . get_permalink() . '" style="background-image: url(' . $bg_image . ')"><div class="next-description"><p class="mast">Next project</p><h3 class="display-2">' . get_the_title() . '</h3></div></a>';
wp_reset_query();
};
echo '</div>';
echo '</div>';
}
From memory, I used this as a starting point (lot a trial and error!). https://gist.github.com/banago/5603826