你仍然可以使用get_posts:

$parents = get_posts(
    array(
        \'posts_per_page\' => -1,
        \'post_type\'      => \'my_custom_post_type\',
        \'fields\'         => \'ids\', // Just get IDs, not objects
        \'tax_query\'      => array(
            array(
                \'taxonomy\' => \'my_custom_tax\',
                \'field\'    => \'slug\',
                \'terms\'    => array(
                    \'foo\',
                    \'bar\',
                ),
            ),
        ),
    )
);

$post_ids = get_posts(
    array(
        \'posts_per_page\'  => -1,
        \'post_parent__in\' => $parents,
        \'post_type\'       => \'my_custom_post_type\',
        \'fields\'          => \'ids\',
        \'meta_query\'       => array(
            array(
                \'key\'   => \'my_custom_field\',
                \'value\' => $foobar,
            ),
        ),
    )
);