Thanks Hussein. But the blog post has not pagination, other than the comments.

I'm aware of that. You just need to set the pagination-var. You're not actually enabling pagination for the blog post.

Give it a try!

Giving both pagination-var worked. You can see it from here: https://stage.bergmedia.co.uk/blog/post.php?s=2017-10-21-blog-test.

Thank you Sir. I can settle for this now.

            <?php
            perch_blog_custom([
        'filter' => 'postSlug',
        'match' => 'eq',
        'value' => perch_get('s'),
        'pagination-var' => 'anything',
        ]);
             ?>


                <?php
                    perch_blog_post_comments(perch_get('s'), [
                'template' => 'comment.html',
                'paginate' => true,
                'count' => 3,
                'sort-order' => 'DESC',
                    'pagination-var' => 'comm',
                ]);
                ?>

I have disabled the pagination as it re-loads the entire page, just to show the rest of the comments.

I used a load more function instead.

Ideally, A database query to load more comment is the best option.

I will give it another try. Just like Hussein said, pagination-var does not work on perch_blog_post_comments.

"It doesn't have to reload the entire page - that's down to your frontend code." Well how will you do it?

Post.php

            <?php
                    PerchSystem::set_var('page_tags.html',
                    perch_blog_post_tags(perch_get('s'), [], true));
                    perch_blog_custom([
                    'filter' => 'postSlug',
                    'match' => 'eq',
                    'paginate' => false,
                    'value' => perch_get('s'),
                    'pagination-var' => 'blogpage',
                    ]);
             ?>

             <?php
                    perch_blog_post_comments(perch_get('s'), [
                    'template' => 'comment.html',
                    'pagination-var' => 'comms',
                    'paginate' => true,
                    'count' => 3,
                    'sort-order' => 'DESC',
                    ]);
             ?>

comment.html

<perch:before>
<div class="row">
    <h2 class="fs-26">Comments and responses</h2>
    <div class="col-lg-12 pd-top-30">
</perch:before>
    <div class="col-lg-12 bor-top pd-top-20 <perch:blog id="perch_item_odd" type="hidden" />" id="comment<perch:blog id="commentID" type="hidden" />" >
<div class="col-lg-2">
    <img class="circle" src="//www.gravatar.com/avatar/<perch:blog id="commentEmail" type="email" label="Email" order="2" hash="md5" required="true" />?s=120&d=mm" width="75" height="75" />
    </div>

<div class="col-lg-10">

    <p rel="bookmark" class="comm-date"><perch:blog id="commentDateTime" format="%d %b %Y %X" type="date" time="true" label="Date" /></p>
    <perch:blog id="commentHTML" encode="false" html="true" type="textarea" label="Message (HTML)" order="4" />
</div>
</div>
<perch:after>
<perch:template path="pagination/comments.html" rescope="parent" />
</div></div>
</perch:after>

pagination/comments.html

<perch:if exists="paging">
  <div class="paging">
    Pagex <perch:blog id="current_page" type="hidden" /> of <perch:blog id="number_of_pages" type="hidden" />
    <perch:if exists="not_first_page">
      <a href="<perch:blog id="prev_url" type="hidden" encode="false" />">Previous</a>
    </perch:if>
    <perch:blog id="page_links" encode="false" type="hidden" />
    <perch:if exists="not_last_page">
      <a href="<perch:blog id="next_url" type="hidden" encode="false" />">Next</a>
    </perch:if>
  </div>
</perch:if>

Loading extra content without page reload is a front-end matter and can be handled with Javascript. It's not Perch-specific.