Auto-loading lib files in Rails 4

Question

I use the following line in an initializer to autoload code in my  lib directory during development   config initializers custom rb     RELOAD LIBS   Dir Rails root    lib      rb   if Rails env development     from Rails 3 Quicktip  Auto reload lib folders in development mode   It works great  but it s too inefficient to use in production- Instead of loading libs on each request  I just want to load them on start up  The same blog has another article describing how to do this   config application rb       Custom directories with classes and modules you want to be autoloadable  config autoload paths     W   config root  lib  config autoload paths    Dir    config root  lib         However  when I switch to that  even in development  I get NoMethodErrors when trying to use the lib functions   Example of one of my lib files   lib extensions rb   Time class eval do   def self milli stamp     Time now strftime   Y m d H M S L   to i   end end   Calling Time milli stamp will throw NoMethodError  I realize others have answered similar questions on SO but they all seem to deal with naming conventions and other issues that I didn t to have to worry about before- My lib classes already worked for per-request loading  I just want to change it to per-startup loading  What s the right way to do this

User · Answer

This might help someone like me that finds this answer when searching for solutions to how Rails handles the class loading ... I found that I had to define a module whose name matched my filename appropriately, rather than just defining a class:

In file lib/development_mail_interceptor.rb (Yes, I'm using code from a Railscast :))

module DevelopmentMailInterceptor
  class DevelopmentMailInterceptor
    def self.delivering_email(message)
      message.subject = "intercepted for: #{message.to} #{message.subject}"
      message.to = "[email protected]"
    end
  end
end

works, but it doesn't load if I hadn't put the class inside a module.

User · Answer

Use config to prepare to load you monkey patches extensions for every request in development mode   config to prepare do  action dispatcher     More importantly  will run upon every request in development  but only once  during boot-up  in production and test   Rails logger info   n--- Loading extensions for   self class     Dir glob    Rails root  lib extensions      rb   sort each do  entry     Rails logger info  Loading extension s     entry      require dependency    entry    end  Rails logger info  --- Loaded extensions for   self class  n    end

User · Answer

Though this does not directly answer the question  but I think it is a good alternative to avoid the question altogether   To avoid all the autoload paths or eager load paths hassle  create a  lib  or a  misc  directory under  app  directory  Place codes as you would normally do in there  and Rails will load files just like how it will load  and reload  model files

User · Answer

I think this may solve your problem    in config application rb   config autoload paths  lt  lt  Rails root join  lib     and keep the right naming convention in lib   in lib foo rb   class Foo end   in lib foo bar rb   class Foo  Bar end  if you really wanna do some monkey patches in file like lib extensions rb  you may manually require it   in config initializers require rb   require    Rails root  lib extensions      P S     Rails 3 Autoload Modules Classes by Bill Harding  And to understand what does Rails exactly do about auto-loading  read Rails autoloading     how it works  and when it doesn t by Simon Coffey

[ruby-on-rails] Auto-loading lib files in Rails 4

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