Archive RSS Email

Model annotation

Jul 2, 2011 • posted by Michael Hartl

A helpful reader has noted that the annotate-models gem used by the Ruby on Rails Tutorial has disappeared from RubyGems. When you try to bundle install, you get this error:

Could not find gem 'annotate-models (= 1.0.4)'
in any of the gem sources listed in your Gemfile.

The solution is to use the annotate gem instead:


gem 'annotate', '2.4.0'

Then run

$ bundle install

as usual.

In order to reproduce the behavior of the annotate command provided by annotate-models, you should use bundle exec and pass the new annotate command the before option:

$ bundle exec annotate --position before

The Ruby on Rails Tutorial book has been updated accordingly.

Michael Hartl

I’m Michael Hartl—author, educator, and entrepreneur. I’m probably best known as the creator of the Ruby on Rails Tutorial, a book and screencast series that together constitute one of the leading introductions to web development. Once called his “favorite book” by Wikipedia founder Jimmy Wales, the Ruby on Rails Tutorial currently has over 150 5-star reviews at Amazon. I’m also (in)famous for creating Tau Day and The Tau Manifesto, which have inspired an international movement dedicated to the proposition that “pi is wrong.” (For example, as a result of The Tau Manifesto, MIT releases their admissions decisions each year at “Tau Time” (6:28 p.m.), and typing tau/2 at Google yields 3.14159…) Finally, I’m a founder of Softcover, a publishing system and sales platform for technical authors, which among other things powers both The Tau Manifesto and the Ruby on Rails Tutorial.

I’m a graduate of Harvard College and have a Ph.D. in Physics from Caltech, where I studied black hole dynamics and was an award-winning instructor in theoretical and computational physics. I’m also an alumnus of Y Combinator, the entrepreneur program that has produced companies such as Dropbox and Airbnb. (Alas, my own Y Combinator startup was neither Dropbox nor Airbnb.)