WordPress自定义文章循环无法获取分类 求技术排查

问题说明 #

在实现WordPress自定义文章类型knowledge_capsules的循环展示时，无法获取文章对应的分类信息，相关代码如下：

循环代码 #

<?php
    $ids = array();
    $pages = get_pages("child_of=".$post->ID);
    if ($pages) {
        foreach ($pages as $page) {
            $ids[] = $page->ID;
        }
    }
    $paged = (get_query_var("paged")) ? get_query_var("paged") : 1;
    $args = array(
        "paged" => $paged,
        "post__in" => $ids,
        "posts_per_page" => 50000,
        "post_type" => "knowledge_capsules",
        "orderby" => "date",
        "order" => "DESC"
    );
    query_posts($args);
    if (have_posts()) : while (have_posts()) : the_post(); 
?>
    <div class="kcIndex_feedItemWrapper" id="postID<?php echo get_the_ID(); ?>">
         
    <!-- Need to add in the lightbox content here and fire it open on click -->    
        <a href="#" data-featherlight="#IssueExpandedContent_<?php echo get_the_ID(); ?>">
        <img src="<?php the_field('knowledgecapsule_teaser_thumbimg'); ?>" title="<?php the_title(); ?>" alt="<?php the_title(); ?>">
        <h4><?php the_title(); ?></h4>
        
              
            <div class="categoriesHere">
            <?php 
        $terms = get_the_terms( get_the_ID(), 'knowledge_capsules' );
        if(!empty($terms)){
        foreach($terms as $term){
            echo $term->name.'<br>';
        }
        }
        ?>
            </div>
            
         
            
        </a>
    
    <!-- Expanded content -->
    <div id="IssueExpandedContent_<?php echo get_the_ID(); ?>">        
        <?php the_field('knowledgecapsule_teaser_embeddcode'); ?>
        <p class="viewFullVideoLink"><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>">View the full video</a></p>
    </div>
        
    </div>
        
    

</div>


<?php endwhile; else: ?>
    <!--<h2>Oh No!!</h2>
    <p><?php _e('Sorry, no posts matched your criteria.'); ?></p>-->
<?php endif; ?>

自定义文章类型注册代码 #

<?php

function prefix_create_custom_post_type() {
    /*
     * The $labels describes how the post type appears.
     */
    $labels = array(
        'name'          => 'Knowledge Capsules', // Plural name
        'singular_name' => 'Knowledge Capsule'   // Singular name
    );

    /*
     * The $supports parameter describes what the post type supports
     */
    $supports = array(
        'title',        // Post title
        'editor',       // Post content
        'excerpt',      // Allows short description
        'author',       // Allows showing and choosing author
        'thumbnail',    // Allows feature images
        'comments',     // Enables comments
        'trackbacks',   // Supports trackbacks
        'revisions',    // Shows autosaved version of the posts
        'custom-fields' // Supports by custom fields
    );

    /*
     * The $args parameter holds important parameters for the custom post type
     */
    $args = array(
        'labels'              => $labels,
        'description'         => 'Post type post knowledge capsule', // Description
        'supports'            => $supports,
        'taxonomies'          => array( 'category', 'post_tag' ), // Allowed taxonomies
        'hierarchical'        => false, // Allows hierarchical categorization, if set to false, the Custom Post Type will behave like Post, else it will behave like Page
        'public'              => true,  // Makes the post type public
        'show_ui'             => true,  // Displays an interface for this post type
        'show_in_menu'        => true,  // Displays in the Admin Menu (the left panel)
        'show_in_nav_menus'   => true,  // Displays in Appearance -> Menus
        'show_in_admin_bar'   => true,  // Displays in the black admin bar
        'menu_position'       => 5,     // The position number in the left menu
        'menu_icon'           => '/wp-content/themes/genesis-nal-new/includes/structure/KC_icon.svg',  // The URL for the icon used for this post type
        'can_export'          => true,  // Allows content export using Tools -> Export
        'has_archive'         => true,  // Enables post type archive (by month, date, or year)
        'exclude_from_search' => false, // Excludes posts of this type in the front-end search result page if set to true, include them if set to false
        'publicly_queryable'  => true,  // Allows queries to be performed on the front-end part if set to true
        'capability_type'     => 'post' // Allows read, edit, delete like “Post”
    );

    register_post_type('knowledge_capsules', $args); //Create a post type with the slug is ‘knowledge_capsules’ and arguments in $args.
}
add_action('init', 'prefix_create_custom_post_type');

?>

问题原因 #

1. 分类法参数错误：循环中调用get_the_terms(get_the_ID(), 'knowledge_capsules')，第二个参数传的是自定义文章类型的slug，但注册文章类型时关联的是默认的category（分类）和post_tag（标签）分类法，此处应该传入category而非文章类型slug。

2. 查询逻辑错误：get_pages()函数默认只获取page类型的页面，而非knowledge_capsules自定义文章类型，因此$ids数组中存储的都是页面ID，用这些ID去查询knowledge_capsules类型的文章，会导致查询不到正确内容，自然无法获取分类。

3. 不规范的查询方式：使用query_posts()会干扰WordPress主查询，容易引发后续查询冲突，建议改用WP_Query。

修复方案 #

1. 修正分类获取代码 #

将循环中的分类获取部分修改为：

<?php 
$terms = get_the_terms( get_the_ID(), 'category' );
if(!empty($terms) && !is_wp_error($terms)){
    foreach($terms as $term){
        echo $term->name.'<br>';
    }
}
?>

• 把第二个参数改为category，匹配注册时关联的分类法。
• 增加!is_wp_error($terms)判断，避免分类查询出错时抛出错误。

2. 修正文章查询逻辑 #

如果是要展示所有knowledge_capsules文章，直接移除post__in参数：

$args = array(
    "paged" => $paged,
    "posts_per_page" => 50000,
    "post_type" => "knowledge_capsules",
    "orderby" => "date",
    "order" => "DESC"
);

如果是要关联某个页面的knowledge_capsules文章，建议通过自定义字段实现：

• 给knowledge_capsules文章添加自定义字段（比如related_page_id），存储关联的页面ID。
• 修改查询参数为：

$args = array(
    "paged" => $paged,
    "posts_per_page" => 50000,
    "post_type" => "knowledge_capsules",
    "orderby" => "date",
    "order" => "DESC",
    "meta_query" => array(
        array(
            'key' => 'related_page_id',
            'value' => $post->ID,
            'compare' => '='
        )
    )
);

3. 替换query_posts为WP_Query #

<?php
$paged = (get_query_var("paged")) ? get_query_var("paged") : 1;
$args = array(
    "paged" => $paged,
    "posts_per_page" => 50000,
    "post_type" => "knowledge_capsules",
    "orderby" => "date",
    "order" => "DESC"
);
$kc_query = new WP_Query($args);
if ($kc_query->have_posts()) : while ($kc_query->have_posts()) : $kc_query->the_post(); 
?>
<!-- 内容部分不变 -->
<?php endwhile; wp_reset_postdata(); else: ?>
<!-- 无内容提示 -->
<?php endif; ?>

• 使用WP_Query创建独立查询，避免干扰主查询。
• 循环结束后调用wp_reset_postdata()恢复主查询的上下文。

内容的提问来源于stack exchange，提问作者dubbs