do shortcode on save post wordpress

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PHP

WordPress

I want to save the content in postmeta where shortcodes are extracted with do_shortcode.
My problem is that he use do_shortcode, but he doesn't take attributes of the shortcode.

the content like:
Hello world my name is [name first="foo" last="bar"].

With this code, I save the content in the postmeta:

function save($post_id){
if (isset($_REQUEST['content'])){
update_post_meta($post_id, 'custom', do_shortcode($_REQUEST['content']));
}
}

shortcode likes this:

function name($atts){
return "firstname".$atts['first'].", lastname".$atts['last'];
}

When I look in phpmyadmin to look the postmeta, i see this:
Hello world my name is firstname, lastname.

How can I fix this problem?