如果计划使用WP的内置图像自定义字段，请在single-project.php （假设仅在单个项目页面上调用库）：

// this will get all images attached to that specific post
$imagequery = new WP_Query(
    array(
    \'post_type\' => \'attachment\',
    \'post_mime_type\' => \'image/jpeg\',
    \'post_parent\' => $post->ID
    ));

if ($imagequery->have_posts()) {
    // loop to present those images here
}
else { // if no images attached to that post
    // fetch all posts from the taxonomy
    $catquery = get_posts(
        array(
        \'post_type\' => \'projects\',
        \'numberposts\' => -1,
        \'yourtaxonomyname\' => \'yourtermname\' // specify the \'category\' here
        ));

    $postids = array();

    if ($catquery) {
        foreach ( $catquery as $onepost ) {
        array_push($postids, $onepost->ID); // make array of post ids
}

    $newimagequery = new WP_Query( // then query these ids to get their images
    array(
    \'post_type\' => \'attachment\',
    \'post_mime_type\' => \'image/jpeg\',
    \'post__in\' => $postids
    ));

if ($newimagequery->have_posts()) {
    // loop to present images from other posts here
}


}