So, I was working on getting a particular view which rattles off a list of categories working to link off to another view that has a Contextual Filter on said category field to list off all matching content items with said value in the field. Similar to Taxonomy terms, but being linked from a select dropdown. I was using the output as link option, with a replacement filter to put the value of the item into the url. Everything was pretty straightforward, except for one little snag. One of my categories had a forward slash in it. Now, normally I would think this / would be url encoded to %2F, but that wasn't happening.
I did some digging, by utilizing hook_views_pre_render to modify what it was sending to the display, and I found that it was in fact running through drupal_encode_path. Here's the full text of that method:
return str_replace('%2F', '/', rawurlencode($path));
As you can see, that's just urlencoding the string you're sending to it, and then decoding the slash. That means that no matter what I do in hook_views_pre_render, I am totally unable to get that / encoded properly for the url. Bummer.
Eventually I hacked it by making a separate view for the offending item (there was ony one), but for now it looks like my best option is to not allow slashes in that particular drop-down.