How to disallow characters in URL titles

Question

We recently ran into an issue with some of our auto-generated URL title on channel entries. It seems that EE will happily allow characters like periods in URL titles. For example if I had a tile like U.S. Tops in EE Installs then the generated URL title is u.s.-tops-in-ee-installs. The periods can become an issue in some cases. Specifically they seem to throw off the EE Session Tracker Array, causing it to be NULL which is what caused our problem. So my questions are:

1. Why does EE even allow these kinds of characters in URL titles?
2. Is there a setting or way to define a list of disallowed characters to be stripped from URL titles?

Answer 1

Pop open your config file: /system/expressionengine/config/config.php

Look for a config option for 'permitted_uri_characters' - if you don't have it, you can add the line:

$config['permitted_uri_chars'] = "a-z 0-9~%.:_\-";

This is what I use (and I think it's the default). But you should be able to just remove the period.

If you use Structure (or similar), there's probably additional steps you'll want to take. So make sure you do proper testing, and so on.