Custom Posts and Posts - next_post_link and previous_post_link not working together

Question

I have regular posts and one custom post type ('SS13') pulled in together on the same page. When you click through to the 'single' page for each the next_post_link and previous_post link only work within their post group (regular posts or 'SS13'). I can't find a solution so that next/previous work across all the posts. CPT is used for organisational purposes in the admin section.

<?php /* Start loop */ ?>
        <?php while (have_posts()) : the_post(); ?>
            <div class="small-10 large-centered columns">
                <article <?php post_class('standard') ?> id="post-<?php the_ID(); ?>"><!-- 'Standard' added to the post class for style -->

                    <div class="row banner">
                        <div class="large-12 columns">
                            <?php if(get_field('standard_banner_image')){ ?>
                            <img src="<?php the_field('standard_banner_image'); ?>" alt="Banner Image" />
                            <?php } ?>
                        </div>
                    </div><!-- end .row -->
                </article>
            </div>

            <!-- Post Navigation -->
            <div class="row">
                <div class="small-12 large-centered columns">
                    <div class="navigation">
<p class="center"><?php next_post_link('%link', '<span class="nextprevious">Next Post:</span>&nbsp;%title', 'FALSE'); ?>&nbsp&nbsp;|&nbsp;&nbsp;<?php previous_post_link('%link', '<span class="nextprevious">Previous Post:</span>&nbsp;%title',  'FALSE'); ?></p>
</div>
                </div>
            </div><!-- end of .row -->
             <?php endwhile; // End the loop ?>

Any help would be great. Thank You.

Answer 1

You will need a filter on get_{$adjacent}_post_where to add your CPT.

function alter_adj_where_wpse_106694($where) {
  $where = str_replace("p.post_type = 'post'","p.post_type IN ('post','yourcpt')",$where);
  return $where;
}
add_filter('get_next_post_where', 'alter_adj_where_wpse_106694' );
add_filter('get_previous_post_where', 'alter_adj_where_wpse_106694' );

There is no flexibility to that callback. It is a simple string replace. If this is your site you should be OK, but if this is a plugin or a theme that you are distributing you need a much more complicated callback to try to compensate for the activity of other plugins and/or themes.