Generating links to the previous and next blog post

This is a reworking of a previous solution by Marc Sanders that can be found in the old Perch forum. While this code is not “battle tested”, hopefully it is of some use to others (like me) who would like this feature.

Post.php

<?php

$slug = perch_get('s'); // sets slug to equal postSlug

$html = perch_blog_post($slug, True);  // stores post in variable to use later

$data = perch_blog_custom(array(
    'filter'=>'postSlug',
    'match'=>'eq',
    'value'=>$slug,
    'skip-template'=>true, 
)); // grabs data of current post

$data = $data[0]; // not sure why this is required, but code breaks without it

$date = $data['postDateTime']; // sets the date variable to the posts published date

$prev = perch_blog_custom(array(
    'count'=>1,
    'filter'=>'postDateTime',
    'match'=>'lt',
    'sort'=>'postDateTime',
    'sort-order'=>'DESC',
    'value'=>$date,
    'template'=>'blog/post_prev.html'
), true); // stores post in a variable to use later

$next = perch_blog_custom(array(
    'count'=>1,
    'filter'=>'postDateTime',
    'match'=>'gt',
    'sort'=>'postDateTime',
    'sort-order'=>'ASC',
    'value'=>$date,
    'template'=>'blog/post_next.html'
), true); // stores post in a variable to use later

?>

<?php
    if ($html) {
        echo $html; // display post
    }

    if (empty($prev)){
        echo '<div class="blog-nav"><a class="disabled">Prev</a>';
    } else {
        echo $prev;
}

if (empty($next)){
    echo '<a class="disabled">Next</a></div>';
} else {
    echo $next;
}

?>

Post_prev.html

<div class="blog-nav">
    <a href="/articles/<perch:blog id="postSlug" />" class="prev">Prev</a>

Post_next.html

<a href="/articles/<perch:blog id="postSlug" />" class="next">Next</a>
</div>