rails の version を変えたい

Question

私の環境にはRails 5.1.6.1が入っているのですが、rails4で書かれた本で勉強したいのでversionを
4.2.2に落としたいです。

googleで調べた記事を参考にやってみましたが、

mkdir test
cd test
gem install bundler
rbenv rehash
rbenv exec bundle install --path vendor/bundle

下記のエラーになりました。

Fetching gem metadata from https://rubygems.org/..........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Bundler could not find compatible versions for gem "bundler":
  In Gemfile:
    rails (= 4.2.2) was resolved to 4.2.2, which depends on
      bundler (< 2.0, >= 1.3.0)

  Current Bundler version:
    bundler (2.0.1)
This Gemfile requires a different version of Bundler.
Perhaps you need to update Bundler by running `gem install bundler`?

Could not find gem 'bundler (< 2.0, >= 1.3.0)', which is required by gem 'rails (=
4.2.2)', in any of the sources.

やり方を知っている方、ぜひ教えてください。

Answer 1

rails (= 4.2.2) was resolved to 4.2.2, which depends on
  bundler (< 2.0, >= 1.3.0)

という文がありますね。
これは、
rails4.2.2はbundler(< 2.0, >= 1.3.0)に依存しています
という意味になります。

なので、bundlerのversionを落とさなければいけません。

# 利用可能なbundlerのversion一覧を確認
$ gem query -ra -n  "^bundler$"

>> *** REMOTE GEMS ***

bundler (2.0.1, 2.0.0, 1.17.3, 1.17.2, 1.17.1, 1.17.0, 1.16.6, 1.16.5, 1.16.4, 1.16.3, 1.16.2, 1.16.1, ...以下略)

参考：初心者は覚えておきたいRubygemsのコマンドまとめ

という結果が出たので、条件を満たす 1.17.3 あたりでもインストールしてみましょうか。

$ gem install bundler -v "1.17.3"

参考：Gemのインストール、バージョン指定など

この状態で再度 bundle install したらどうでしょうか？

---

バージョンの読み方についてはここが参考になりますね。
参考：【Rails】Gemfileのバージョン指定の書き方

Comments

[siruku6]

退会済みでしたね・・・

Answer 2

$ rails _4.2.2_ new 作りたいアプリ名

rails newのときに_でバージョンを指定するとでそのバージョンのrailsアプリが作られます

Comments

[退会済みユーザー]

rails _4.1.1_ new todo
で作ってみたのですが、bin/rails sをした時に下記のエラーになりました。

/Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/values/time_zone.rb:285: warning: circular argument reference - now
=> Booting WEBrick
=> Rails 4.1.1 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Notice: server is listening on all interfaces (0.0.0.0). Consider using 127.0.0.1 (--binding option)
=> Ctrl-C to shutdown server
/Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:121: warning: constant ::Fixnum is deprecated
/Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:121: warning: constant ::Bignum is deprecated
Exiting
/Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>': stack level too deep (SystemStackError)
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/activesupport-4.1.1/lib/active_support/core_ext/numeric/conversions.rb:131:in `block (2 levels) in <class:Numeric>'
... 4789 levels...
from /Users/username/.rbenv/versions/2.4.4/lib/ruby/2.4.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/username/source/rails/todo/bin/spring:13:in `<top (required)>'
from bin/rails:3:in `load'
from bin/rails:3:in `<main>'