The reason that wrq:path_info/2 is returning ‘undefined’ for you, though, is likely that this dispatch line for env_resource looks different than the line for the default demo resource webmachine creates. If you go back to my previous post, you’ll see three lines of comments at the top of env_resource.erl. These are the dispatch lines you need (they tell Webmachine where to extract that ‘env’ token from).

The dispatch for your webmachine instance is in mywebdemo_sup.erl (search for “Dispatch”). Add the two lines from my post to that Dispatch list, recompile, restart, and you’ll be set. Note that if you’ve copied the code from my examples into mywebdemo.erl, you’ll want to replace “env_resource” in my example dispatches with “mywebdemo” in yours.

Warning to future readers: the last paragraph is incorrect if you downloaded Webmachine after this reply was written. Dispatch configuration is now handled in priv/dispatch.conf.

If I patch your resource into “mywebdemo”, “wrq:path_info” always returns ‘undefined’. The Dispatch wiki page talks about “wrq:path_tokens”, “wrq:get_path_info”, and “wrq:disp_path”; but not “wrq:path_info”.

I think your post assumes familiarity w/ webmachine and I am trying to use your example to gain that …. kind of a catch22 for me