Why won't Rails 4 uninstall? - ruby-on-rails

Question

After uninstalling Rails 4(RC1) I still get Rails 4 apps generated with rails new.
➲ rails -v
Rails 4.0.0.rc1
➲ which rails
/Users/brandon/.rvm/gems/ruby-1.9.3-p392/bin/rails
➲ gem uninstall rails
Select gem to uninstall:
1. rails-3.2.13
2. rails-3.2.3
3. All versions
>
What's the cleanest way to fix this?

Answer 1

It is quite easy.
gem uninstall rails -v=4.0.0.rc1
gem uninstall railties
gem install rails -v 3.2.13
gem update --system
rails -v
By using commands above I was able to install older version of rails as needed :)

Answer 2

Rails does not come as an all-in-one package. You have a base Rails gem, plus it's many dependencies:
Action Mailer
Action Pack
Active Record
Active Resource
Active Support
Bundler
Railties <---- (contains generators)
Sprockets adapter for Rails
To get rid of your Rails 4 installation as a whole, you must remove all of these gems.
The easiest way to do this is to delete your entire gem folder, then reinstall whatever you need.

Answer 3

Try specifying your installed version:
gem uninstall rails -v=4.0.0.rc1
EDIT:
If you've already uninstalled (which you have), the following should work:
gem update --system
rails _3.2.2_ new app_name # or whatever version you're on

Answer 4

Fortunately, this worked as a simple fix for me:
Please note that in order to shift back to 3.2.13 (or whatever version you'd like to go back to), you must remove Railties as well as Rails.
Just do:
gem uninstall rails
Then, select the version of Rails 4 you have and delete it.
Then, do:
gem uninstall railties
And do the same thing.
When I uninstalled the Rails 4 version of railties, it told me that dependencies for a couple gems (coffee-rails and sass-rails) wouldn't be met. So I just did the same thing with both of them as I did above (such as, gem uninstall sass-rails), and deleted their Rails 4 versions as well. For example, for sass-rails, I had a version installed called sass-rails-4.0.0.rc1, so I uninstalled that version).
And that's it; the terminal will list 3.2.13 as your current Rails version, and new apps will be generated from this version as well.

Answer 5

TL;DR:
The simplest and safest solution to the immediate problem is
gem uninstall railties
Slightly Longer & More Complete Approach
If you want to uninstall everything that gem install rails installed, you can get a list of commands to run with this:
gem dependency rails --pipe | ruby -ne 'puts $_.gsub(/\([0-9\. <>=~,]*\)/,"")' | ruby -ne 'puts "gem uninstall #{$_}"'
Copy those and run them one-by-one, and for each one you'll be told what else depends on it, and asked if you want to go ahead with uninstallation. If you see anything in the list that is not part of rails (say you've installed something else that needs that version of active_record) then leave it, otherwise go ahead and uninstall.
The longer explanation
The version displayed is taken from the version of the railties gem, which is not uninstalled by uninstalling the rails gem.
If you open the rails executable with
vim `which rails`
(or the equivalent with the editor of your choice) you'll see the code at the bottom that decides which version of rails to use based on the version of railties:
#!/usr/bin/env ruby_noexec_wrapper
#
# This file was generated by RubyGems.
#
# The application 'railties' is installed as part of a gem, and
# this file is here to facilitate running it.
#
require 'rubygems'
version = ">= 0"
if ARGV.first
str = ARGV.first
str = str.dup.force_encoding("BINARY") if str.respond_to? :force_encoding
if str =~ /\A_(.*)_\z/
version = $1
ARGV.shift
end
end
gem 'railties', version
load Gem.bin_path('railties', 'rails', version)
The simplest solution, therefore, is just to gem install railsties. There is no solution built-into RubyGems (that I can find) that will detect which other gems were installed with rails and are no longer used by anything else and uninstall them. RubyGems does not have the idea of an exclusive dependency, so even though nothing else besides rails uses railties, you're still stuck having to know that it (and several other things) are left over and must be manually uninstalled. This is not ideal, but it's what we've got right now, and it's not that bad, especially if you use the solution above to find and remove all the rails dependencies.