If I have a ruby class which I want to use it as a library in a rails app, how (what folder) should I include it in the application?
I want to use the class in my controller. Do I just simply use 'require' to include the class?
You can just do a require in the controller assuming the file is somewhere in your load path. I follow a few simple strategies:
If its a class that adds plugin like behavior but isnt quite large enough to write a plugin, I just put it in config/initializers since they the lib is in the load path and all the files are required for you on startup. No additional requires needed.
The other option is to put them in the lib directory and just require them when you need them. If you are using rails 3, the lib directory is not a part of the load path and you will need to add it.
I'd recommend throwing it in the lib folder - you then can require it from your config/environment.rb file and if I recall correctly, that should be all you need to do.
i using ruby on rails programing language for the making a very simple project which is need to create folder hierarchy just like yahoomail folder. but i need to also subfolder create in this directory so is support ruby on rails?
Yes, it does.
You can create recursive directories using
require 'fileutils'
FileUtils.mkdir_p 'my/path/to/something'
Following links can be useful for you
http://rosettacode.org/wiki/Walk_a_directory/Recursively#Ruby,
Ruby: how do I recursively find and remove empty directories?
I have a question regarding how to call ruby classes that reside outside of rails app structure.
I have few Ruby classes that are used/invoked from cron job periodically.
I would like to use the same ruby classes to be invoked from a rails controller
after user creates a model object.
Is it possible to invoke code that resides outside of rails app directory without copying the ruby classes
over. I am mostly concerned that both the classes will be out of sync soon if I have to copy them to rails app folder.
Ruby app reside in, /usr/local/railsapp1 . The ruby classes reside in /usr/local/other_task/
Any suggestions would be of great help.
thanks
You can. Just use in your config/environment.rb
config.load_paths << "/usr/local/other_task/"
This will load whatever classes in that folder into your rails environment.
But the path is hard-coded in this case, so you have to be careful when deploying.
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'm trying to understand what does and doesn't work in Ruby gems (primarily from the perspective of creating one for myself to reuse functionality from one project to the next).
When you create a Ruby gem, are you limited to including only Ruby functionality or could you create a gem that consisted of Rails templates, CSS files and JavaScripts?
If so, how would the user of the gem access those resources in a Rails project (besides adding a 'config gem' statement to the environment.rb file?
No it doesn't. Gems are code libraries, not static files.
When you load a gem, you don't move the files to your public directory. You load a ruby file and get access to a module. So, you can only execute ruby code within it.
But, your ruby code can give you some helpers allowing you to easily build your design for example.
If you want to include some static file resources in each of your ruby projects, I'd see two solutions:
Create a template project, including all the css, javascript etc. that you use every time. You can take suspenders as an example of this.
Create a new repository with all these static files and add it as a submodule (with git or svn) and include it in each of your projects.
The first solution would be my favorite, but you might want to take the other one.
As dmathieu notes, gems are for ruby libraries that are installed in the system load path, not for things that go into your project directory. If you do want to package your rails project skeleton as a gem, though, it would be simple enough to have a small ruby executable that served as a generator to copy the skeleton project tree into a target directory. You could then package the whole thing up into a gem, your skeleton files could sit in the gem directory, and you could say generate_new_project someproject to copy them into your new project directory.
You can easily add partials and other HAML, Builder, or ERB views. The following structure should work:
# in my_gem/rails/init.rb
ActionController::Base.append_view_path(File.expand_path(File.join(File.dirname(__FILE__), '..', 'views')))
# in my_gem/views/my_gem/_some_partial.html.erb
This is a partial from MyGem!
# in your_rails_app/views/some_controller/some_view.html.erb:
<%= render :partial => '/my_gem/some_partial' -%>
That doesn't directly answer your question about static files, though. Often the best bet is a generator that copies the CSS, JS, and other files to your public directory. Alternatively, you could use a StaticFilesController and put the static files in that views directory.