This post originated from an RSS feed registered with Ruby Buzz by Bob Silva. Original Post: RAILS_ROOT and Dir.chdir Feed Title: Rails Video Tutorials Feed URL: http://www.railtie.net/xml/rss/feed.xml Feed Description: A growing collection of screencasts that show you how to use the many facets of the wonderful world of rails. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Bob Silva Latest Posts From Rails Video Tutorials

It's been awhile since I've blogged on Rails, got diverted to a Novell to Windows conversion over Christmas break. A local community college requested emergency assistance with completing their conversion and asked us to do it in 2 weeks. My team and I got it done but it was a hell of a lot of work. Now that I'm back to programming, I ran into a little annoyance last night that took awhile to troubleshoot down. I'm working on a little app to provide a web interface to my book collection. My book repository is located elsewhere on my harddrive so I used Dir.chdir to move to the root of the repository.

To make a long story short, DO NOT use Dir.chdir in your Rails Applications. RAILS_ROOT, which is used to locate dependencies is a relative path. If you change the working directory of your Rails application, Rails may/will have problems loading dependencies. In my case, I used Dir.chdir to move to then iterate the publisher directories and add books found onto the publisher.books has_many association. This promptly failed with Publisher::Book uninitialized constant errors. The dependency loading mechanism uses RAILS_ROOT to find items in your load_paths and being a relative path, changes if you change the current working directory.

I believe one solution, which I didn't test, would be to set RAILS_ROOT to an absolute path in your environment.rb. The solution I chose was to not chdir but use a full path in each Directory or File operation i used. And now you know.