URL Rewriting: Name instead of ID

[eluser]perfectsam[/eluser]
[quote author="WanWizard" date="1279641818"]
Thank you all for your solutions.

@WanWizard
My structure is indeed as you described. I took your solution and my code looks like this now:

Code:

if (is_numeric($author_id))
    {
        $author = $this->author_db->getByID($author_id);
        redirect('authors/show/'.$author->getName());
    }
    else
    {
        $author = $this->author_db->getByName($author_id);
    }

Now I only have to write a function that converts the name (+special chars) into a conform URL segment, e.g. John Doe -> john_doe