Rbenv: Start with new ruby and rails versions

Check for the new ruby and rails versions
https://www.ruby-lang.org/en/downloads/
https://rubygems.org/gems/rails/versions

Suppose we are going to install Ruby – 2.4.1 & Rails – 5.1.3

Get rbenv into action

1. $ rbenv install --list # Gets the list of ruby versions available

$ rbenv install 2.4.1

ruby-build: definition not found: 2.4.1

The following versions contain `2.4.1' in the name:
  rbx-2.4.1

See all available versions with `rbenv install --list'.

If the version you need is missing, try upgrading ruby-build:

  brew update && brew upgrade ruby-build

Oops..!

rbenv cannot find the version: 2.4.1

Upgrade ruby-build

Mac:

$ brew upgrade ruby-build --HEAD

Now install ruby 2.4.1

$ rbenv install 2.4.1

Create a new gemset:

$ rbenv gemset create 2.4.1 demo-app
That set up a directory for you in ~/.rbenv/versions/2.4.1/gemsets/demo-app

Set the ruby version to the newest

$ rbenv local 2.4.1

$ rbenv version
=> 2.4.1

    Activate New Gemset


For activating a gemset we need to create a .rbenv-gemsets file in the current directory.

$ touch .rbenv-gemsets
$ echo demo-app > .rbenv-gemsets

Check active gemset:

$ rbenv gemset active

Install Rails 5.1.3

$ gem install rails -v '5.1.3'
$ gem install --no-rdoc --no-ri rails -v '5.1.3' # skips the documentation

Later we can delete this .rbenv-gemsets file and add a new file named ‘.ruby-gemset’ in the rails project directory. I cannot see any other good way of doing this. If anybody know about some other good way of doing this please give a comment.

Create a New Rails app

$ rails new demo-app

$ rm .rbenv-gemsets

$ cd demo-app
$ touch .ruby-gemset
$ echo demo-app > .ruby-gemset
$ touch .ruby-version
$ echo 2.4.1 > .ruby-version
$ rails s
=> Booting Puma
=> Rails 5.1.3 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.9.1 (ruby 2.4.1-p111), codename: Private Caller
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop

Goto http://localhost:3000/

rails-5-new.png

Done! Lets go…

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Two ways to load files in Rails

There are two ways that files get loaded in Rails:

It is registered in the autoload process, and you reference a constant that corresponds to the file name. For instance, if you have app/controllers/pages_controller.rb and reference PagesController, app/controllers/pages_controller.rb will automatically be loaded. This happens for a preset list of directories in the load path. This is a feature of Rails, and is not part of the normal Ruby load process.
Files are explicitly required. If a file is required, Ruby looks through the entire list of paths in your load paths, and find the first case where the file you required is in the load path. You can see the entire load path by inspecting $LOAD_PATH (an alias for $:).

Since lib is in your load path, you have two options: either name your files with the same names as the constants, so Rails will automatically pick them up when you reference the constant in question, or explicitly require the module.

I also notice that you might be confused about another thing. ApplicationController is not the root object in the system. Observe:

module MyModule
  def im_awesome
    puts "#{self} is so awesome"
  end
end
class ApplicationController < ActionController::Base
  include MyModule
end

class AnotherClass
end

AnotherClass.new.im_awesome
# NoMethodError: undefined method `im_awesome' for #

You will need to include the module into whatever class you want to use it in.

class AnotherClass
  include MyModule
end

AnotherClass.new.im_awesome
# AnotherClass is so awesome

Of course, in order to be able to include the module in the first place, you’ll need to have it available (using either of the techniques above).

Reference: This note is from a blog/site that I looked for some knowledge.

Get information about your Rails Environment

To get information about your Rails Environment Rails, Ruby, Rack versions use the following command,

$ rake about

About your application's environment
Ruby version 1.9.2 (i686-linux)
RubyGems version 1.8.10
Rack version 1.3
Rails version 3.1.3
JavaScript Runtime therubyracer (V8)
Active Record version 3.1.3
Action Pack version 3.1.3
Active Resource version 3.1.3
Action Mailer version 3.1.3
Active Support version 3.1.3
Middleware Rack::Cache, ActionDispatch::Static, Rack::Lock, Rack::Runtime, Rack::MethodOverride, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::RemoteIp, Rack::Sendfile, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::Head, Rack::ConditionalGet, Rack::ETag, ActionDispatch::BestStandardsSupport, Warden::Manager, OmniAuth::Builder
Application root /home/abhi/my_app
Environment development
Database adapter mysql2
Database schema version 20120704103548