通过在元数据键上添加下划线，可以使元数据私有，并且在自定义字段列表中不可见。一、 e。_accesstype_visibility

您可以在WP Developer文档中找到更多详细信息，https://developer.wordpress.org/plugins/metadata/managing-post-metadata/#hidden-custom-fields

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EDIT 24.7.2020

// first hook we\'re filtering, second our callback, third priority, fourth # of parameters
add_filter( \'is_protected_meta\', \'my_prefix_is_protected_meta\', 10, 3 );
// available parameters can be found on the filter documentation
function my_prefix_is_protected_meta( $protected, $meta_key, $meta_type ) {
    // Force custom meta key to be protected
    if ( \'my_meta_key\' === $meta_key ) {
        $protected = true;
    }
    // Return filtered value so WP can continue whatever it was doing with the value
    return $protected;
}