I'm developing a Rails engine, and so I've taken some looks on existing ones. I noticed that many of them have files in app, but also in lib and vendor.
It's clear to me that I should put any code that should be replaceable by the host app into the app folder (e.g. when having a model app/user.rb, the host app can easily have its own app/user.rb file and use this one instead of the engine one's).
But I'm unsure, when I have to put stuff in to lib, and when into vendor? I thought, that in vendor, I should only put "external" code from other developers or projects, that I want to use in my project, and in lib I put my own additional libraries that I'm actually working on in the project. But why, for example, does WiceGrid put stuff into its wice_grid/vendor/assets directory? It doesn't look to me like external code, but code that is developed only for WiceGrid and hence should be in the lib directory?
Update
While experimenting a bit, I noticed that all code in the lib folder is not reloaded while developing the engine (I guess the same is the case for the vendor directory), so I should put them into a folder within app, but where exactly?
For example, I have a file lib/iq_list_controller.rb that holds some class and instance methods for ApplicationController which I mix into it in engine.rb like this:
initializer "wice_grid_railtie.configure_rails_initialization" do |app|
ActiveSupport.on_load(:action_controller) do
extend IqList::Controller::ClassMethods
include IqList::Controller::InstanceMethods
end
end
Where should I put this file so Ruby properly finds it?
Regarding the development reloading issue, if the lib folder is a natural home for your files, then add it to Rails' load path with something like:
module MyEngine
class Engine < ::Rails::Engine
config.autoload_paths << File.expand_path("../../lib", __FILE__)
end
end
Regarding the specific case of vendor assets, it seems reasonable to place your engine's assets in app/assets, where they will be found by the host Rails app.
if you want things to be autoloaded then put them in /app. Otherwise I think that anything in /lib should be manually required. I generally believe that autoloading the lib folder is bad practice.
your basic code for MVC comes in app folder.now suppose you have a generic method/module which is frequently used,so to implement DRYness for your code...all generic and common utilities can be simply put in lib folder.
theres a beautiful explaination when to use lib and using lib folder in rails
I want to overwrite a file of a rails engine, but that file is in that engine's lib/rails directory. When I take the same file and drop it in my lib/rails directory it doesn't overwrite the file. Seems like rails handles the lib directory differently than say files that are in the app directory.
Also I can't place this file in the initializer folder (per this solution) as the filename is the same as an exisiting file that is needed. What is the proper way of doing this?
The best way I have found to solve this problem is by adding
require "#{Rails.root}/lib/path/to/file"
at the end of config/application.rb. The pollution is minimal, and achieves the same effect as the override would.
Currently using it in a Spree project to override lib/spree_samples.rb.
Edit
Found a better way in this answer:
Overloading lib files from gem mounted as engine
Essentially, put the file you want to override in your config/initializers directory.
Since the latest Rails 3 release is not auto-loading modules and classes from lib anymore,
what would be the best way to load them?
From github:
A few changes were done in this commit:
Do not autoload code in *lib* for applications (now you need to explicitly
require them). This makes an application behave closer to an engine
(code in lib is still autoloaded for plugins);
As of Rails 2.3.9, there is a setting in config/application.rb in which you can specify directories that contain files you want autoloaded.
From application.rb:
# Custom directories with classes and modules you want to be autoloadable.
# config.autoload_paths += %W(#{config.root}/extras)
# Autoload lib/ folder including all subdirectories
config.autoload_paths += Dir["#{config.root}/lib/**/"]
Source: Rails 3 Quicktip: Autoload lib directory including all subdirectories, avoid lazy loading
Please mind that files contained in the lib folder are only loaded when the server is started. If you want the comfort to autoreload those files, read: Rails 3 Quicktip: Auto reload lib folders in development mode. Be aware that this is not meant for a production environment since the permanent reload slows down the machine.
The magic of autoloading stuff
I think the option controlling the folders from which autoloading stuff gets done has been sufficiently covered in other answers. However, in case someone else is having trouble stuff loaded though they've had their autoload paths modified as required, then this answer tries to explain what is the magic behind this autoload thing.
So when it comes to loading stuff from subdirectories there's a gotcha or a convention you should be aware. Sometimes the Ruby/Rails magic (this time mostly Rails) can make it difficult to understand why something is happening. Any module declared in the autoload paths will only be loaded if the module name corresponds to the parent directory name. So in case you try to put into lib/my_stuff/bar.rb something like:
module Foo
class Bar
end
end
It will not be loaded automagically. Then again if you rename the parent dir to foo thus hosting your module at path: lib/foo/bar.rb. It will be there for you. Another option is to name the file you want autoloaded by the module name. Obviously there can only be one file by that name then. In case you need to split your stuff into many files you could of course use that one file to require other files, but I don't recommend that, because then when on development mode and you modify those other files then Rails is unable to automagically reload them for you. But if you really want you could have one file by the module name that then specifies the actual files required to use the module. So you could have two files: lib/my_stuff/bar.rb and lib/my_stuff/foo.rb and the former being the same as above and the latter containing a single line: require "bar" and that would work just the same.
P.S. I feel compelled to add one more important thing. As of lately, whenever I want to have something in the lib directory that needs to get autoloaded, I tend to start thinking that if this is something that I'm actually developing specifically for this project (which it usually is, it might some day turn into a "static" snippet of code used in many projects or a git submodule, etc.. in which case it definitely should be in the lib folder) then perhaps its place is not in the lib folder at all. Perhaps it should be in a subfolder under the app folder· I have a feeling that this is the new rails way of doing things. Obviously, the same magic is in work wherever in you autoload paths you put your stuff in so it's good to these things. Anyway, this is just my thoughts on the subject. You are free to disagree. :)
UPDATE: About the type of magic..
As severin pointed out in his comment, the core "autoload a module mechanism" sure is part of Ruby, but the autoload paths stuff isn't. You don't need Rails to do autoload :Foo, File.join(Rails.root, "lib", "my_stuff", "bar"). And when you would try to reference the module Foo for the first time then it would be loaded for you. However what Rails does is it gives us a way to try and load stuff automagically from registered folders and this has been implemented in such a way that it needs to assume something about the naming conventions. If it had not been implemented like that, then every time you reference something that's not currently loaded it would have to go through all of the files in all of the autoload folders and check if any of them contains what you were trying to reference. This in turn would defeat the idea of autoloading and autoreloading. However, with these conventions in place it can deduct from the module/class your trying to load where that might be defined and just load that.
Warning: if you want to load the 'monkey patch' or 'open class' from your 'lib' folder, don't use the 'autoload' approach!!!
"config.autoload_paths" approach: only works if you are loading a class that defined only in ONE place. If some class has been already defined somewhere else, then you can't load it again by this approach.
"config/initializer/load_rb_file.rb" approach: always works! whatever the target class is a new class or an "open class" or "monkey patch" for existing class, it always works!
For more details , see: https://stackoverflow.com/a/6797707/445908
Very similar, but I think this is a little more elegant:
config.autoload_paths += Dir["#{config.root}/lib", "#{config.root}/lib/**/"]
In my case I was trying to simply load a file directly under the lib dir.
Within application.rb...
require '/lib/this_file.rb'
wasn't working, even in console and then when I tried
require './lib/this_file.rb'
and rails loads the file perfectly.
I'm still pretty noob and I'm not sure why this works but it works. If someone would like to explain it to me I'd appreciate it :D I hope this helps someone either way.
I had the same problem. Here is how I solved it. The solution loads the lib directory and all the subdirectories (not only the direct). Of course you can use this for all directories.
# application.rb
config.autoload_paths += %W(#{config.root}/lib)
config.autoload_paths += Dir["#{config.root}/lib/**/"]
As of Rails 5, it is recommended to put the lib folder under app directory or instead create other meaningful name spaces for the folder as services , presenters, features etc and put it under app directory for auto loading by rails.
Please check this GitHub Discussion Link as well.
config.autoload_paths does not work for me. I solve it in other way
Ruby on rails 3 do not automatic reload (autoload) code from /lib folder. I solve it by putting inside ApplicationController
Dir["lib/**/*.rb"].each do |path|
require_dependency path
end
If only certain files need access to the modules in lib, just add a require statement to the files that need it. For example, if one model needs to access one module, add:
require 'mymodule'
at the top of the model.rb file.
Spell the filename correctly.
Seriously. I battled with a class for an hour because the class was Governance::ArchitectureBoard and the file was in lib/governance/architecture_baord.rb (transposed O and A in "board")
Seems obvious in retrospect, but it was the devil tracking that down. If the class is not defined in the file that Rails expects it to be in based on munging the class name, it is simply not going to find it.
There are several reasons you could have problems loading from lib - see here for details - http://www.williambharding.com/blog/technology/rails-3-autoload-modules-and-classes-in-production/
fix autoload path
threadsafe related
naming relating
...
I understand the benefit of putting classes, modules, etc. in the lib folder in Rails, but I haven't been able to find a clean way of testing these files. For the most part, it seems like unit tests would be the logical approach.
I guess my question is: What is the "rails way" for testing lib files?
Your lib directory is not automatically loaded by rails.
You can use ActiveSupport::Dependencies to override const_missing. Basically rails will try to load your constants when it boots, if they are undefined or not in memory it will look at your load paths.
If you have a file like my_class.rb, rails expects it to be MyClass.
The beauty of this is if you have some stuff in your lib directory, you don't have to require it with a relative path you can just say require 'something', instead of require 'lib/something'.
I have a ruby on rails project with scaffolding , views, layouts, models and such. I also have some standalone ruby (.rb) files which i would like to include in my afforementioned project. Is it possible to simply call these methods defined in these rb files by placing them somewhere and calling them from the controller or so?
If not, how can i go about and add them?
Any assistance would be highly appreciated thanks
Place your code in the lib folder, then create a new initializer file in config/initializers and require the files u want.