// set current category $categories = get_the_category(); $category = $categories[0]; $cat_ID = $category->cat_ID; // get next post link $next_post = get_adjacent_post( true, '', false ); if( $next_post ) { echo '<a href="' . get_permalink( $next_post->ID ) . '">Next post</a>'; } else { $first = new WP_Query( array( 'post_type' => 'project', 'post_status' => 'publish', 'posts_per_page' => 1, 'order' => 'ASC', 'cat' => $cat_ID )); $first->the_post(); echo '<a href="' . get_permalink() . '">Next post</a>'; wp_reset_query(); }; // show prev post link $prev_post = get_adjacent_post( true, '', true ); if( $prev_post ) { echo '<a href="' . get_permalink( $prev_post->ID ) . '">Prev post</a>'; } else { $last = new WP_Query( array( 'post_type' => 'project', 'post_status' => 'publish', 'posts_per_page' => 1, 'order' => 'DESC', 'cat' => $cat_ID )); $last->the_post(); echo '<a href="' . get_permalink() . '">Prev post</a>'; wp_reset_query(); };