Never Render a POST!

There are a few things in web design that you should never do, yet people seem to do them quite often.  I'll give a little explanation of this one first so my non-technical audience can tag along.  PHPers, please pay attention.

Web browsers understand two verbs when making a transaction with a web server: POST and GET. Generally, POST means you're sending information to the server, and GET means you're getting information back. In a perfect world, every web page you ever see would be the result of a GET, and every time you POSTed you would be redirected to a GETable page. But we don't live in a perfect world, do we?

The culprits are poorly-designed web-forms. Good web-forms like google.com submit via GET, which puts your search arguments in a query string after the url, like so: http://www.google.com/search?q=awesome . This is good because now you can copy that url and paste it to someone else, and they can see your search results too.

POST, on the other hand, sends the form's information to the server invisibly. If you render a page on a POST, you can't paste the url to someone else, because they will not have posted that information. If you hit Refresh on a posted page, or try to navigate back past one with your Back button, your browser will warn you that you are posting again. You have to POST again in order to see that page again. And that's annoying. Your browser can't even cache the page because it knows this is a dynamically generated response to a POST, so it will load slowly too.

POST should only be used for actions that change something on the server's side. They should never render content, but rather redirect to a GETable page to do that.  When you redirect, the POST's target page is stricken from the record, so can no longer navigate back to it and accidentally POST again.  Hooray!