您可以通过将一个简单的函数挂接到save_post 钩

add_action(\'save_post\',\'my_rating_field\');
function my_rating_field($post_id){
    global $post;
        // verify if this is an auto save routine. 
        // If it is our form has not been submitted, so we dont want to do anything
        if ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE ) 
            return;

        // verify this came from the our screen and with proper authorization,
        // because save_post can be triggered at other times
        if ( !wp_verify_nonce( $_POST[\'myplugin_noncename\'], plugin_basename( __FILE__ ) ) )
            return;
        // Check post type
        if ($post->post_type != "YOUR_POST_TYPE_NAME")
            return;

        // OK, we\'re authenticated: we need to find and save the data
    $rating = get_post_meta($post_id,\'rating\',true);
    //if field not exists create it and give it the value of one
    if (empty($rating) || !isset($rating)){
        update_post_meta($post_id,\'rating\',1);
    }
}