.htaccess vanity url not redirecting properly - apache

Question

I've got a blog subdirectory on my website (foo.com/blog), and I'm following a tutorial that offers a brief explanation of vanity urls.
Basically, I'm trying to get it so that when the user navigates to 'foo.com/blog/xyz' the 'xyz' variable (username) redirects the user to:
foo.com/blog/profile.php?username=xyz
but still displays as:
foo.com/blog/xyz
The code in the tutorial doesn't work, so I've been relying on code in the youtube comments under it:
RewriteBase /
RewriteEngine on
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule .* - [L]
RewriteRule ^(.*)$ http://www.foo.com/blog/profile.php?username=$1 [NC]
The problem is, when I try to navigate to 'foo.com/blog/xyz' it instead redirects to:
foo.com/blog/profile.php?username=blog/xyz
So obviously the username is being set to blog/xyz instead of xyz itself.
Likewise, if navigate to foo.com/xyz, it redirects to where it is supposed to go:
http://www.foo.com/blog/profile.php?username=xyz
But displays this url as it is instead of showing up as foo.com/blog/xyz (like how reddit shows up as reddit.com/u/username for users)
So it appears I have two problems:
1) I can't figure out how to make it so that it only does the rewrite when I navigate to foo.com/blog/xyz rather than foo.com/xyz (.htaccess is in public_html -- I tried moving it to public_html/blog but it didn't work)
2) I can't figure out how to get it to display as blog/xyz instead of blog/profile?php?username=xyz
I don't know much about apache, and I really just need to get this one piece of code right so I can continue bashing my head against the wall with the rest of the tutorial. Does anyone know what I'm doing wrong?

Answer 1

Well, you never mentioned in your rule set anything about how to treat that/bog part of the request path. Do it...
RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^/?blog/(.*)$ /blog/profile.php?username=$1 [L]
I also cleaned up a few other issues with the code you posted which would prevent it from working as you claim at all.
And a general hint: you should always prefer to place such rules inside the http servers (virtual) host configuration instead of using dynamic configuration files (.htaccess style files). Those files are notoriously error prone, hard to debug and they really slow down the server. They are only provided as a last option for situations where you do not have control over the host configuration (read: really cheap hosting service providers) or if you have an application that relies on writing its own rewrite rules (which is an obvious security nightmare).