这里：您需要创建一个元框，因此首先使用add\\u meta\\u box（）

// Hook into WordPress add_meta_boxes action
add_action( \'add_meta_boxes\', \'add_Businesses_custom_metabox\' );

/**
 * Add meta box function
 */
function add_Businesses_custom_metabox() {
    add_meta_box( \'custom-metabox\', __( \'Businesses\' ), \'Businesses_custom_metabox\', \'events\', \'side\', \'high\' );
}

在这里，您可以看到，我使用“事件”作为我要注册此元框的post类型，我的回调函数是：Businesses_custom_metabox() 它是实际显示metabox的函数，因此我们对其进行如下定义：

/**
 * Display the metabox
 */
function Businesses_custom_metabox($post) {
    global $post,$current_user;
    //remember the current $post object
    $real_post = $post;
    //get curent user info (we need the ID)
    get_currentuserinfo();
    //create nonce
    echo \'<input type="hidden" name="Businesses_meta_box_nonce" value="\', wp_create_nonce(basename(__FILE__)), \'" />\';
    //get saved meta
    $selected = get_post_meta( $post->ID, \'a_businesses\', true );
    //create a query for all of the user businesses posts
    $Businesses_query = new WP_Query();
    $Businesses_query->query(array(
                            \'post_type\' => \'posts\',
                            \'posts_per_page\' => -1,
                            \'author\' => $current_user->ID));
    if ($Businesses_query->have_posts()){
        echo \'<select name="a_businesses" id="a_businesses">\';
        //loop over all post and add them to the select dropdown
        while ($Businesses_query->have_posts()){
            $Businesses_query->the_post();
            echo \'<option value="\'.$post->ID.\'" \';
            if ( $post->ID == $selected){
                echo \'selected="selected"\';
            }
            echo \'>\'.$post->post_title .\'</option>\';
        }
        echo \'<select>\';
    }
    //reset the query and the $post to its real value
    wp_reset_query();
    $post = $real_post;
}

我试着对其中的任何一点进行评论，以便你能更好地理解。最后一件事是在保存帖子时处理元盒：

//hook to save the post meta
add_action( \'save_post\', \'save_Businesses_custom_metabox\' );
/**
 * Process the custom metabox fields
 */
function save_Businesses_custom_metabox( $post_id ) {
    global $post;
    // verify nonce
    if (!wp_verify_nonce($_POST[\'Businesses_meta_box_nonce\'], basename(__FILE__))) {
        return $post_id;
    }
    // check autosave
    if (defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE) {
        return $post_id;
    }
    // check permissions
    if (\'events\' == $_POST[\'post_type\']) {
        if (!current_user_can(\'edit_page\', $post_id)) {
            return $post_id;
        }
    } elseif (!current_user_can(\'edit_post\', $post_id)) {
        return $post_id;
    }

    if( $_POST ) {
        $old = get_post_meta($post_id, \'a_businesses\', true);
        $new = $_POST[\'a_businesses\'];
        if ($new && $new != $old){
            update_post_meta($post_id, \'a_businesses\', $new);
        }
    }
}