Weird Rails 3 Route Problem

I am using simple_captcha. It worked find until I add the following line to routes.rb

match ":controller(/:action)", :constraints => {:controller => /sandbox\/[^\/]+/}

The captcha image is not showing and the log shows the following error message.

Started GET "/simple_captcha/8cdf70c193dc8823f281828f11c250e1739883da?time=1294644088" for 127.0.0.1 at Sun Jan 09 23:21:29 -0800 2011

AbstractController::Actio开发者_Go百科nNotFound (The action '8cdf70c193dc8823f281828f11c250e1739883da' could not be found for SimpleCaptchaController):

Why does the line in the routes affect simple_captcha?

Thanks.

Sam

Lets assume the constraint does not exist for now. Given :controller(/:action) matches and tries to match a particular controller and then an action, the route /simple_captcha/8cdf70c193dc8823f281828f11c250e1739883da matches simple_captcha as a controller and 8cdf70c193dc8823f281828f11c250e1739883da as a action. You could try more of a ":controller/(:id)" as a route matcher.

I fixed the problem by modifying a line.

From:

match ":controller(/:action)", :constraints => {:controller => /sandbox\/[^\/]+/}

To:

match ":controller(/:action)", :controller => /sandbox\/[^\/]+/

I thought they are the same but obviously they are not. How do they differ?