我已经在我的平台上添加了一个内容分级系统，作者可以在其中选择他们的帖子适合的受众。目前，这些选项可用：

未评级

G

PG

R

我用于在编辑后页面上显示评级选项的代码是：

// Article Content Rating
add_action( \'add_meta_boxes\', \'rating_select_box\' );
function rating_select_box() {
    add_meta_box(
        \'rating_select_box\', // id, used as the html id att
        __( \'Content Rating (optional)\' ), // meta box title
        \'rating_select_cb\', // callback function, spits out the content
        \'post\', // post type or page. This adds to posts only
        \'side\', // context, where on the screen
        \'low\' // priority, where should this go in the context
    );

}

function rating_select_cb( $post ) {
    global $wpdb;
    $value = get_post_meta($post->ID, \'rating\', true);
    echo \'<div class="misc-pub-section misc-pub-section-last"><span id="timestamp"><label>Article Content Rating: </label>\';

    $ratings = array(
        1 => \' G \',
        2 => \' PG \',
        3 => \' R \',
    );

    echo \'<select name="rating">\';
    echo \'<option value=""\' . ((($value == \'\') || !isset($ratings[$value])) ? \' selected="selected"\' : \'\') . \'> Unrated </option>\';

    // output each rating as an option
    foreach ($ratings as $id => $text) {
        echo \'<option value="\' . $id . \'"\' . (($value == $id) ? \' selected="selected"\' : \'\') . \'">\' . $text. \'</option>\';
    }
    echo \'</select>\';

    echo \'</span></div>\';
}

add_action( \'save_post\', \'save_metadata\');

function save_metadata($postid)
{   
    if ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE ) return false;
    if ( !current_user_can( \'edit_page\', $postid ) ) return false;
    if( empty($postid) ) return false;


    if ( is_null($_REQUEST["rating"]) ) {
        delete_post_meta($postid, \'rating\');
    } else {
        update_post_meta($postid, \'rating\', $_REQUEST[\'rating\']);
    }

}
// END Article Content Rating

现在，问题是，我要添加什么代码single.php 显示他们的选择？例如，如果作者选择了PG，那么我想echo \'Content Rating: PG\'; 或者如果是默认（未评级），我想echo \'Content Rating: Unrated\';. 这怎么可能？理想情况下，在我的平台流量很大的情况下，服务器上的解决方案是轻量级的。

$value = get_post_meta($post->ID, \'rating\', true);

$ratings = array(
    1 => \' G \',
    2 => \' PG \',
    3 => \' R \',
);

if (!empty($ratings[$value])) {
  echo \'<p>Content Rating : \'.$ratings[$value].\'</p>\';
} else {
  echo \'<p>Content Rating : Unrated</p>\';
}

function wpse_78113_get_rating( $pid )
{
    $ratings = array(
        1 => \' G \',
        2 => \' PG \',
        3 => \' R \',
    );
    $meta = get_post_meta( $pid, \'rating\' );
        // var_dump($meta);

    if( empty($meta) || empty($meta[0]) )
        return \'Content rating: Unrated\';

    return \'Content rating: \' . $ratings[$meta[0]];
}

if ( is_null($_REQUEST["rating"]) ) {
    delete_post_meta($postid, \'rating\');
} else {
    update_post_meta($postid, \'rating\', $_REQUEST[\'rating\']);
}