apache - Understanding difference between redirect and rewrite .htaccess

Question

I'd like to understand the difference between redirecting and rewriting a URL using .htaccess. So here's an example: Say I have a link like www.abc.com/ index.php?page=product_types&cat=88 (call this the "original" url)

But when the user types in abc.com/shoes (let's call this the "desired" url), they need to see the contents of the above link. To accomplish this, I would do this:

Options +FollowSymLinks
RewriteEngine on
RewriteBase /
RewriteRule ^(.*)shoes(.*)$ index.php?page=product_types&cat=88

Nothing wrong with this code and it does the trick. However, if I type in the original url in the address bar, the content comes up, but the url does not change. So it remains as www.abc.com/index.php?page=product_types&cat=88

But what if I wanted the desired url (/shoes) to show up in the address bar if I typed in www.abc.com/ index.php?page=product_types&cat=88? How would this be accomplished using .htaccess? Am I running into a potential loop?

Answer 1

Some of the explanation can be found here: https://stackoverflow.com/a/11711948/851273

The gist is that a rewrite happens solely on the server, the client (browser) is blind to it. The browser sends a request and gets content, it is none the wiser to what happened on the server in order to serve the request.

A redirect is a server response to a request, that tells the client (browser) to submit a new request. The browser asks for a url, this url is what's in the location bar, the server gets that request and responds with a redirect, the browser gets the response and loads the URL in the server's response. The URL in the location bar is now the new URL and the browser sends a request for the new URL.

Simply rewriting internally on the server does absolutely nothing to URLs in the wild. If google or reddit or whatever site has a link to www.abc.com/index.php?page=product_types&cat=88, your internal server rewrite rule does absolutely nothing to that, nor to anyone who clicks on that link, or any client that happens to request that URL for any reason whatsoever. All the rewrite rule does is internally change something that contains shoes to /index.php?page=product_types&cat=88 within the server.

If you want make it so a request is made for the index.php page with all of the query strings, you can tell the client (browser) to redirect to the nicer looking URL. You need to be careful because rewrite rules loop and your redirect will be internally rewritten which will cause a redirect which will be internally rewritten, etc.. causing a loop and will throw a 500 Server Error. So you can match specifically to the request itself:

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9} /index.php?page=product_types&cat=88
RewriteRule ^/?index.php$ /shoes [L,R=301]

This should only be used to make it so links in the wild get pointed to the right place. You must ensure that your content is generating the correct links. That means everything on your site is using the /shoes link instead of the /index.php?page=product_types&cat=88 link.