How to compose redirect nginx?

Question

Nginx

There is a website with a forum on it.
the link to the topic looks like this:
site.ru/viewtopic.php?t=74384
but in the Yandex search there are many links to the pages of the site of this type:
site.ru/?t=74384
Tell me how to make a 301 redirect so that when you request the address site. ru/?t=74384 was issued site.ru/viewtopic.php?t=74384
Thank you!

Answer 1

location = / {
    if ($arg_t != '') {
      return 301 "/viewtopic.php?t=$arg_t";
    }
  }