I.NFECTIO.US

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.

Twenty years ago, I learned about sex for the first time. All my friends said they were doing it, although I think most of them were full of it and just wanted to look cool. I didn't know much about sex back then but I'd read about it in The Joy of Sex and watched it on TV. There's something about actually doing it that you don't understand through those other mediums.

Learning about testing has been a very similar experience for me. I've known about it for awhile, all my programmer friends say they're doing it, and I've even read Test Driven Development By Example by Kent Beck. But doing it for the first time is a completely different experience. At first, I didn't know exactly what I was doing, I was aimlessly exploring the inputs and outputs, and before I knew it, I'd had my first testing orgasm. The tests I was writing discovered a serious bug in my code. That's when it clicked for me, really understanding what test driven development is about. If I had written the tests first, the specific bug they revealed wouldn't have existed in the first place.

Now that I've popped my testing cherry, I want to keep doing it, and much like my first sexual partner, Rails makes it easy. And when you get comfortable with your new partner, you can introduce great toys like ZenTest that will improve your experience.

While researching what some of the YAML syntax was doing in Ben Bleything's article on DRY'ing up your database config, I ran across the YAML Cookbook. I've only ever used YAML for my database.yml and test fixtures, so I was really surprised to see the power YAML affords the Ruby programmer. Check it out, you will find a few things useful in your fixtures and I'm sure other ideas on it's use will come to you as you see how powerful it is.