使用中的链接iguanarama\'s 回答,您的更新代码是:
<?php if (has_term( \'type-1\', \'projecttype\' ) ) { ?>
<div class="holder">
    <?php if ( have_posts() ) : ?>
    <div class="container-fluid">
        <div class="project-paginat">
            <?php if(get_post_meta($post->ID, "_type", true)){ ?>
                <ul class="list-inline">
                    <li><a href="<?php echo get_home_url(); ?>/our-work">Back to Our Work</a></li>
                    <li>>>  <?php echo get_post_meta($post->ID, "_type", true); ?></li>
                    <li>
                    <?php
                        if( get_adjacent_post(false, \'\', true) ) {
                            previous_post_link(\'%link\', \'< Previous Project\', true, \'\', \'projectcategory\');
                        } else {
                            $args = array(
                                \'posts_per_page\' => 1,
                                \'order\'          => \'DESC\',
                                \'category_name\'  => \'projectcategory\',
                            );
                            $first = new WP_Query( $args ); $first->the_post();
                            echo \'<a href="\' . get_permalink() . \'">< Previous Project</a>\';
                            wp_reset_query();
                        };
                    ?>
                    </li>
                    <li>
                    <?php
                        if( get_adjacent_post(false, \'\', false) ) {
                            next_post_link(\'%link\', \'Next Project >\', true, \'\', \'projectcategory\');
                        } else {
                            $args = array(
                                \'posts_per_page\' => 1,
                                \'order\'          => \'ASC\',
                                \'category_name\'  => \'projectcategory\',
                            );
                            $last = new WP_Query( $args ); $last->the_post();
                            echo \'<a href="\' . get_permalink() . \'">Next Project ></a>\';
                            wp_reset_query();
                        };
                    ?>
                    </li>
                </ul>
            <?php } else {
                echo \'<p>There Is No Project Type To Display.</p>\';
            } ?>
        </div>
Reference: http://wplancer.com/infinite-next-and-previous-post-looping-in-wordpress/