pagination for custom post type archive page

Question

I have a custom post type (gallery). On the archive page, I'm limiting the display to 12 items, with pagination links below. This works as it should, but I'm getting error notices:

Notice: Undefined variable: query in /var/www/wp-content/themes/sal-custom_strap/archive-gallery.php on line 78

Notice: Trying to get property 'max_num_pages' of non-object in /var/www/wp-content/themes/sal-custom_strap/archive-gallery.php on line 78

Here is the code (line 78 is the second to last line) :

 <div class="card-deck justify-content-center" id="gallery-results">    

                        <?php
                        while ( have_posts() ) :
                            the_post();
                
                            get_template_part( 'template-parts/content', 'gallery' );
                
                        endwhile; // End of the loop.
                        ?>
    
    </div><!-- .card-deck -->
    <div class="nav-center">
        <div class="nav-next"><?php previous_posts_link( '<–– Previous' ); ?></div>
        <div class="nav-previous"><?php next_posts_link( 'Next ––>', $query->max_num_pages ); ?></div>
    </div>

I wrote this code a while ago and haven't been using php since, so I suspect I am forgetting something basic. What am I missing?

thanks.

Answer 1

You're using $query-> but there is no variable named $query, it's just pulled out of thin air, it has to come from somewhere, so PHP is generating notices complaining about it. It would be like if I answered the question with "you need to apply gabobobobble" or some other made up word.

So instead, look up next_posts_link:

https://developer.wordpress.org/reference/functions/next_posts_link/

The official docs say the second parameter is:

$max_page

• (int) (Optional) Max pages. Default 0.

Since it's optional you can remove it.