More notes from a Rails 3.0pre upgrade

This is a follow-on from my piece on how I got the (development version of) Catapult Magazine up and running with Rails 3.0pre. If you haven’t already done so, I’d recommend you read that first.

Catapult makes use of the permalink_fu plugin which fails in Rails 3. It fails because of a reliance on the evaluate_attribute_method method which no longer exists in version 3. I’ve temporarily worked around that by replacing it with class_eval, but lately I’ve been using friendly_id a lot more and I suspect I’ll be focussing on porting to that if it works cleanly in Rails 3.

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A dependency I’ve long wanted to part with is has_many_polymorphs. I’m using it to manage the categorisation of issues and posts but all that’s ever really saved me is one table/model, so perhaps now is the time to clean up the models and lose that dependency.

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open_id_authentication uses a config.to_prepare block to include itself in ActionController::Base but that’ll work just as well if I add

include OpenIdAuthentication

to my ApplicationController, so that’s what I’ve done. I suspect a number of other changes will be needed (there’s a reference to config.gem in there) but so far, so good.

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The key issue I’ve run into is that the init.rb files in my gem plugins aren’t run automatically, meaning that in addition, say, to declaring a model has_attached_file (for paperclip) I also need to require ‘paperclip’. That’s not totally unreasonable, but in a complex app it could be quite time consuming and begins to move away from the sense that a plugin/gem is a self-contained unit.

Looking through the new rails source I found the method that loads the init.rb files for plugins installed in vendor/plugins. Rails::Plugin::Vendored (in railties/lib/rails/plugin.rb) contains:

initializer :load_init_rb, :before => :load_application_initializers do |app|
  file   = "#{@path}/init.rb"
  config = app.config
  eval File.read(file), binding, file if File.file?(file)
end

but that only looks through those, not gem plugins. It wouldn’t be too hard to add some code in the initializer to glob the relevant folder and load those files but I’ve not had time yet to decide if that’s my best way forward.