插件建议在这里被认为是离题的。一种解决方案是在帖子中添加一个元框，如下所示：

Add to Functions.php

/** Add Post Metabox **/
function add_custom_meta_box() {
    add_meta_box(
        \'pick_post\', // $id
        \'Pick Post\', // $title 
        \'show_custom_meta_box_pick_post\', // $callback
        \'agenda\', // $page
        \'side\', // $context
        \'high\'); // $priority
}
add_action(\'add_meta_boxes\', \'add_custom_meta_box\');

/** Post Metabox Callback (show some stuff in box) **/
function show_custom_meta_box_pick_post() {
    $doelArr = get_posts( array( \'post_type\' => \'doel\', \'orderby\' => \'title\', \'order\' => \'ASC\', \'posts_per_page\' => -1 ) );
    $meta_doel = get_post_meta($post->ID, \'_doellist\', true);
?>
    <input type="hidden" name="info_meta_box_nonce" value="<?php echo wp_create_nonce(basename(__FILE__)); ?>" />
    <strong>Associated Doel</strong>
        <br />
    <select id="selectdoel" name="_doellist">
        <option value="">Select Doel</option>
    <?php foreach($doelArr as $doel) : setup_postdata( $doel ) ?>
        <?php if($doel->ID == $meta_doel) : ?>
            <option value="<?php echo $doel->ID; ?>" selected="selected"><?php echo $doel->post_title; ?></option>
        <?php else : ?>
            <option value="<?php echo $doel->ID; ?>"><?php echo $doel->post_title; ?></option>
        <?php endif; ?>
    <?php endforeach; ?>
    </select>
}

/** Save Our Meta-data **/
function save_custom_meta($post_id) {
    global $post;

    // check autosave
    if ((defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE) || (!current_user_can(\'edit_post\', $post_id)))
        return $post_id;

    if($post->post_type == \'agenda\')
    {
        // Doel Selection List Check
        if(isset($_POST[\'_doellist\']) && $_POST[\'_doellist\'] != \'\')
            update_post_meta($post_id, \'_doellist\', strip_tags($_POST[\'_doellist\']));
        else
            delete_post_meta($post_id, \'_doellist\');
    }
}

这样做的目的是创建一个包含Doel帖子下拉列表的小型元框，然后将Doel帖子ID保存为元值。您可以在任何时候通过将议程ID传递给get_post_meta() 作用

$meta_doel = get_post_meta($post->ID, \'_doellist\', true);

然后你可以像这样得到整个Doel帖子：

$doel_post = get_post($meta_doel);