我在和古腾堡比赛，我有点困惑它应该如何保存给梅塔。这是我的自定义帖子和元数据：

add_action( \'init\', function() {
    register_post_type( \'game\', [
        \'label\' => \'Games\',
        \'public\' => true,
        \'supports\' => [ \'editor\', \'custom-fields\' ],
        \'show_in_rest\' => true,
    ] );

    register_meta( \'game\', \'logo\', [
        \'single\' => true,
        \'show_in_rest\' => true,
        \'description\'  => \'A meta key associated with a string meta value.\',
        \'type\' => \'string\'
    ] );
} );

和我的Block JS文件：

( function( blocks, i18n, element ) {

    var el = element.createElement;
    var MediaUploadButton = wp.blocks.MediaUploadButton;
    var BlockControls = wp.blocks.BlockControls;

    blocks.registerBlockType( \'game-post/meta\', {
        title: i18n.__( \'Game\' ),
        description: i18n.__( \'Meta Box for Game\' ),
        icon: \'businessman\',
        category: \'common\',
        attributes: { 
            logo: {
                type: \'string\',
                source: \'meta\',
                meta: \'logo\'
            }   
        },
        edit: function(props) {
            console.log(props.attributes);
            var mediaURL = props.attributes.logo;
            return el(\'div\', {
                classname: mediaURL ? \'image-active\' : \'image-inactive\'
            }, el(\'input\', {
                defaultValue: mediaURL,
                type: \'text\',
                onChange: function(e) {
                    props.setAttributes({ logo: e.target.value });
                }  
            }));
        },
        save: function(props) {
            return el( \'img\', { src: props.attributes.logo } );
        }
    } );

} )(
    window.wp.blocks,
    window.wp.i18n,
    window.wp.element,
);

我从WP Gutenberg Handbook. 已创建属性等，但值为空，且未保存元字段。控制台登录编辑函数总是返回null，因为没有meta属性。我做错了什么？如果我将属性源更改为attribute, 该字段已正确保存。

add_action( \'init\', function() {
    register_post_type( \'game\', [
        \'label\' => \'Games\',
        \'public\' => true,
        \'supports\' => [ \'editor\', \'custom-fields\' ],
        \'show_in_rest\' => true,
    ] );

    register_post_meta( \'game\', \'logo\', [
        \'single\' => true,
        \'show_in_rest\' => true,
        \'description\'  => \'A meta key associated with a string meta value.\',
        \'type\' => \'string\'
    ] );
} );

registerBlockType( \'game-post/meta\', {
    //...
    save: () => null,
});

register_meta( \'post\', \'logo\', [
    \'single\' => true,
    \'show_in_rest\' => true,
    \'description\'  => \'A meta key associated with a string meta value.\',
    \'type\' => \'string\'
] );