Ruby on Rails 3 - Reload lib directory for each request

I'm creating a new engine for a rails 3 application. As you can guess, this engine is in the lib directory of my application.

However, i have some problems developing it. Indeed, I need to restart my server each time I change something in the engine.

Is there a way to avoid this ?

Can I force rails to completely reload the lib directory or a specific file and his requirements for each request ?

Thanks for your help :)

Solution 1:

I couldn't get any of the above to work for me so I dug in the Rails code a bit and came up with this:

New file: config/initializers/reload_lib.rb

if Rails.env == "development"
  lib_reloader = ActiveSupport::FileUpdateChecker.new(Dir["lib/**/*"]) do
    Rails.application.reload_routes! # or do something better here
  end

  # For Rails 5.1+
  ActiveSupport::Reloader.to_prepare do
    lib_reloader.execute_if_updated
  end

  # For Rails pre-5.1 
  ActionDispatch::Callbacks.to_prepare do
    lib_reloader.execute_if_updated
  end

end

Yes, I know it's disgusting but it's a hack. There might be a better way to trigger a full reload, but this works for me. My specific use case was a Rack app mounted to a Rails route so I needed it to reload as I worked on it in development.

Basically what it does is it checks if any files in /lib have changed (modified timestamp) since last loaded and then triggers a reload if they change.

I might also mention I have this in my config/application.rb

config.autoload_paths += %W(#{config.root}/lib)
config.autoload_paths += Dir["#{config.root}/lib/**/"]

Which just by default makes sure everything in my lib directory gets loaded.

Yays!

Solution 2:

TL;DR

• put this in config/application.rb

  config.eager_load_paths += ["#{Rails.root}/lib"]

• remove require statements for your lib files

Go!

Let me explain in detail.

I don't know why this answer is accepted, since it doesn't help with reloading lib folder on each request. First I thought that it works for Rails 2, but the question clearly states that it was for Rails 3 and the release date of 3.0.0 is before the date of the answer.

Other answers seem over-complicated or don't provide a real solution.

I decided to investigate things a little, because it was bothering me and I've even found out that people have a workaround for this and it involves saving lib files inside app/models in development and then moving it to /lib when done. We can do better, right?

My solution is tested against:

• Rails 3.0.20
• Rails 3.1.12
• Rails 3.2.13
• Rails 4.0.0.rc1

Put this into your config/application.rb:

# in config/application.rb
config.eager_load_paths += ["#{Rails.root}/lib"]

That's it!™

Make sure you put it here since it will not work if you put it in config/environments/development.rb, for example.

Make sure your remove all the require statements for your /lib code since require statements will also cause this solution to not work.

This code implicitly requires your code, so if you do environment checks (which are unnecessary) and instead of the above code, you decide to write something like this:

# in config/application.rb
config.eager_load_paths += ["#{Rails.root}/lib"] if Rails.env.development?

you should watch out on the old require statements, since they are still required on all the non-development environments, in this scenario.

So if you still decide to do environment checks, make sure you do inverse checks for require statements. Otherwise you'll get bitten!

require "beer_creator" unless Rails.env.development?

You might think that writing entire paragraph about something that's unnecessary is also unnecessary, but I think that warning people about something that's necessary when doing something unnecessary is also necessary.

If you would like to know more about this topic, check out this little tutorial.

Solution 3:

Since we are talking Rails, the easiest way is to 'require' your lib/* .rb files using 'require_dependency'. So long as the controller/helper/etc (.rb files under app/) uses require_dependency instead of just require reloading works, without the need to do anything funky.

Before I went down that track, the only solution that worked was the one on hemju.com, but I really did not want to have to hack the ApplicationController for Dev speed.

Solution 4:

You have to add

config.autoload_paths += %W(#{config.root}/lib)

to your Application class in config/application.rb

https://rails.lighthouseapp.com/projects/8994/tickets/5218-rails-3-rc-does-not-autoload-from-lib

Solution 5:

In RAILS 3, here's the secret sauce to auto-reload lib files. The code below's a bit overkill, for the example, but it's what I did to make it work. You can change the message in YoYo#gogo and see it on the screen each page load. Remove out the initializer and it stays the same.

/config/initializers/lib_reload.rb (new file)

ActiveSupport::Dependencies.explicitly_unloadable_constants << 'YoYo'
ActiveSupport::Dependencies.autoload_once_paths.delete(File.expand_path(File.dirname(__FILE__))+'/lib')

/lib/yo_yo.rb

class YoYo
  def gogo
    "OH HAI THERE"
  end
end

/app/controllers/home_controller

require 'yo_yo'
class HomeController < ApplicationController
  def index
    @message = YoYo.new.gogo
  end
end