是否有任何WP内置功能可以完成正确的工作？

不

[我]必须为此编写自定义查询吗？

编号使用get_terms(). 这里有一个例子。

添加wpse_99513_adjacent_category 类的函数。php主题文件，并按如下方式调用：

$category_ids = new wpse_99513_adjacent_category( \'category\', \'id\', false );

要获取下一个分类，请使用以下内容：

$next_category = $category_ids->next( $category );

以前的作品也是这样：

$previous_category = $category_ids->previous( $category );

对于跳过空类别的Slug，请使用：

$category_ids = new wpse_99513_adjacent_category( \'category\', \'slug\' );

class wpse_99513_adjacent_category {

    public $sorted_taxonomies;

    /**
     * @param string Taxonomy name. Defaults to \'category\'.
     * @param string Sort key. Defaults to \'id\'.
     * @param boolean Whether to show empty (no posts) taxonomies.
     */
    public function __construct( $taxonomy = \'category\', $order_by = \'id\', $skip_empty = true ) {

        $this->sorted_taxonomies = get_terms(
            $taxonomy,
            array(
                \'get\'          => $skip_empty ? \'\' : \'all\',
                \'fields\'       => \'ids\',
                \'hierarchical\' => false,
                \'order\'        => \'ASC\',
                \'orderby\'      => $order_by,
            )
        );
    }

    /**
     * @param int Taxonomy ID.
     * @return int|bool Next taxonomy ID or false if this ID is last one. False if this ID is not in the list.
     */
    public function next( $taxonomy_id ) {

        $current_index = array_search( $taxonomy_id, $this->sorted_taxonomies );

        if ( false !== $current_index && isset( $this->sorted_taxonomies[ $current_index + 1 ] ) )
            return $this->sorted_taxonomies[ $current_index + 1 ];

        return false;
    }

    /**
     * @param int Taxonomy ID.
     * @return int|bool Previous taxonomy ID or false if this ID is last one. False if this ID is not in the list.
     */
    public function previous( $taxonomy_id ) {

        $current_index = array_search( $taxonomy_id, $this->sorted_taxonomies );

        if ( false !== $current_index && isset( $this->sorted_taxonomies[ $current_index - 1 ] ) )
            return $this->sorted_taxonomies[ $current_index - 1 ];

        return false;
    }
}

这就是我想到的。也许不是最好的，但很有效：）

假设我们在自定义分类类别页面上，并且希望转到下一个

// get the term used on this current taxonomy page
$term = get_term_by( \'slug\', get_query_var(\'term\'), get_query_var(\'taxonomy\') );

//set your arguments
$args = array(
     \'hide_empty\' => 0,
     \'orderby\' => \'name\',
     \'order\' => \'DESC\',
);

    //set your vars
$cycletaxonomy = \'author\';
    // get all terms in a custom taxonomy

$cycleterms = get_terms($taxonomy, $args);

    // A for loop to cycle through all terms
for ($x=0; $x<count($cycleterms); $x++){
            // assign current cycled category slug - i could have used id too actually
    $thisslug = $cycleterms[$x]->slug;

    if ($curslug == $thisslug) {
        $nextslug = $cycleterms[$x+1]->slug;
        $prevslug = $cycleterms[$x-1]->slug;
        echo $nextslug;
        echo $prevslug;
                    // now do what you want with this slug - like putting it into a link tag
    }
};

我不确定WordPress中是否有bulit函数，但您可以

使用下一个和上一个帖子ID获取下一个和上一个页面及其类别。

基于Akmur答案的小更新

$term = get_term_by(\'slug\', get_query_var(\'term\'), get_query_var(\'taxonomy\'));
$curslug = $term->name;
$args = array(
    \'hide_empty\' => 0,
);
$cycletaxonomy = \'YOUR_TERM\';
// get all terms in a custom taxonomy
$cycleterms = get_terms($taxonomy, $args);
// A for loop to cycle through all terms
for ($x = 0; $x < count($cycleterms); $x++) {
    // assign current cycled category slug - i could have used id too actually
    $thisslug = $cycleterms[$x]->name;

    if ($curslug == $thisslug) {
        $nextslug = $cycleterms[$x + 1]->name;
        $prevslug = $cycleterms[$x - 1]->name;
        echo \'<ul class="post-nav">\';
        if (!empty($nextslug)) {
            echo \'<li class="next"><a href="\' . get_term_link(intval($cycleterms[$x + 1]->term_id), \'YOUR_TERM\') . \'">\' . $nextslug . \'</a><li>\';
        }
        if (!empty($prevslug)) {
            echo \'<li class="previous"><a href="\' . get_term_link(intval($cycleterms[$x - 1]->term_id), \'YOUR_TERM\') . \'">\' . $prevslug . \'</a><li>\';
        }
        echo \'</ul>\';
        // now do what you want with this slug - like putting it into a link tag
    }
}

将此函数放在函数中。php：

function adjacent_post_by_category( $category, $direction, $content ) {

    // Info
    $postIDs = array();
    $currentPost = get_the_ID();


    // Get posts based on category
    $postArray = get_posts( array(

        \'category\' => $category,
        \'orderby\'=>\'post_date\',
        \'order\'=> \'DESC\'

    ) );


    // Get post IDs
    foreach ( $postArray as $thepost ):

        $postIDs[] = $thepost->ID;

    endforeach;


    // Get prev and next post ID
    $currentIndex = array_search( $currentPost, $postIDs );
    $prevID = $postIDs[ $currentIndex - 1 ];
    $nextID = $postIDs[ $currentIndex + 1 ];


    // Return information
    if( $direction == \'next\' AND $nextID ):

        return \'<a rel="next" href="\' . get_permalink( $nextID ) . \'">\' . $content . \'</a>\';

    elseif( $direction == \'prev\' AND $prevID ):

        return \'<a rel="prev" href="\' . get_permalink( $prevID ) . \'">\' . $content . \'</a>\';

    else:

        return false;

    endif;

}

<?php echo adjacent_post_by_category( 10, \'prev\', \'Show previous post\' ); ?>

<?php echo adjacent_post_by_category( 10, \'next\', \'Show next post\' ); ?>