我创建了两种自定义帖子类型，buildings 和availabilities, 并添加了一个关于可用性的查询，以选择它所属的建筑，但我似乎无法保存它。

add_action(\'admin_init\', \'p2p2_add_building_metabox\');

function p2p2_add_building_metabox(){
add_meta_box( 
    \'building_availability\', 
    __(\'Building\', \'bandpress\'), 
    \'p2p2_building_availability_metabox\', 
    \'availabilities\', 
    \'side\', 
    \'default\', 
    array( \'id\' => \'p2p2_building\') 
);}

function p2p2_building_availability_metabox($post, $args) {
    wp_nonce_field( plugin_basename( __FILE__ ), \'p2p2_building_nonce\' );
    $building_id = get_post_meta($post->ID, \'p2p2_building\', true);

    echo "<p>Select The Building of This Availability</p>";
    echo "<select id=\'p2p2_building\' name=\'p2p2_building\'>";

    // Query the buildings here
    $query = new WP_Query( \'post_type=building\' );
    while ( $query->have_posts() ) {
        $query->the_post();
        $id = get_the_ID();
        $selected = "";

        if ($id == $author_id) {
            $selected = \' selected="selected"\';
        }
        echo \'<option\' . $selected . \' value=\' . $id . \'>\' . get_the_title() . \'</option>\';
    }

    echo "</select>";
}
 
add_action(\'save_post\', \'p2p2_save_building_metabox\', 1, 2);
function p2p2_save_building_metabox($post_id, $post){
    // Don\'t wanna save this now, right?
    if ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE )
        return;
    
    if ( !isset( $_POST[\'p2p2_building_nonce\'] ) )
        return;

    if ( !wp_verify_nonce( $_POST[\'p2p2_building_nonce\'], plugin_basename( __FILE__ ) ) )
        return;

    // We do want to save? Ok!
    $key = \'p2p2_building\';
    $value = $_POST["p2p2_building"];
    if ( get_post_meta( $post->ID, $key, FALSE ) ) { // If the custom field already has a value
        update_post_meta( $post->ID, $key, $value );
    } else { // If the custom field doesn\'t have a value
        add_post_meta( $post->ID, $key, $value );
    }

    if ( !$value )
        delete_post_meta( $post->ID, $key ); // Delete if blank
}