How to gemify a Rails (engine) plugin?

Question

I have a engine style Rails plugin from which I can create a gem using Jeweler. But when I require it in my Rails environment (or erb) the models within the plugin are not loaded. I have followed a number of tutorials and read just about everything on the subject.

# environment.rb
config.gem 'myengine'

# in irb
require 'myengine'

I have unpacked the gem and verified that all files are present. My init.rb has been moved to a new folder called 'rails' as per. All files in 'lib' are automatically added to the $LOAD_PATH, so require 'myengine' runs lib/myengine.rb. I verified this by putting a puts 'hello' within.

Is it because of the physical presence of plugins in a known place that Rails can add all the models, controller etc. to the relevant load_paths? Do I need to replicate this manually when using a gem?

Would gemspec require_paths be a way of adding additional paths other than lib? I assume however that Rails does not just require every single file, but loads them on demand hence the need for the filename and class name to match?

Answer 1

%w{ models controllers helpers }.each do |dir|
  path = File.join(File.dirname(__FILE__), 'app', dir) + '/'

  $LOAD_PATH << path

  puts 'requiring'
  Dir.new(path).entries.each do |file|
    if file =~ /\.rb/
      puts file
      require file
    end
  end
end

By adding the above to lib/myengine.rb all the models/controllers are required. But like I said in my question this is unlikely to be a good way forward.

Answer 2

Offhand I'd say the part about adding those directories to the search path is right on. What you shouldn't need to do is require each file manually (as you allude to in your last sentence). What Rails does when you reference a non-existent constant is to search for a file with the same name (underscored of course) in the load path.

If for some reason you can not abide by the constraint (think about it long and hard) then you are going to need to dig deeper into Rails and see how the reloading mechanism works so you can tie into it properly in development mode.

Answer 3

The problem was the files (in app) where not being added to the gem because when using Jeweler it only automatically adds files to required_paths which are committed to git.