ruby-on-rails - 如何升级 Rails？

Question

我是 Ruby 和 Rails 的新手，对所有这些命令行 melarky 也是陌生的。所以请多多包涵。

我已经按照各种教程安装了 RubyGems、Homebrew、RVM、Rails 等。

我想我现在已经完成了所有这些，但是当我输入时:

rails --version

我明白了，3.2.12。我注意到 Rails 4 已经出来了。我如何升级到这个版本？

如果我这样做:

gem install rails

甚至在做:

gem update rails

我仍然得到 3.2.12。

有什么想法吗？

更新

在这里尝试几个选项时，我收到此消息......

Michaels-MacBook-Pro:~ ParanoidAndroid$ gem install rails --version=4.0
Building native extensions.  This could take a while...
ERROR:  Error installing rails:
    ERROR: Failed to build gem native extension.

    /usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/local/rvm/rubies/ruby-1.9.3-p392/bin/ruby
    --with-atomic_reference-dir
    --without-atomic_reference-dir
    --with-atomic_reference-include
    --without-atomic_reference-include=${atomic_reference-dir}/include
    --with-atomic_reference-lib
    --without-atomic_reference-lib=${atomic_reference-dir}/lib
/usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/mkmf.rb:461:in `try_link0'
    from /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/mkmf.rb:712:in `try_run'
    from extconf.rb:26:in `<main>'


Gem files will remain installed in /usr/local/rvm/gems/ruby-1.9.3-p392/gems/atomic-1.1.14 for inspection.
Results logged to /usr/local/rvm/gems/ruby-1.9.3-p392/gems/atomic-1.1.14/ext/gem_make.out

似乎发生了错误。还有其他想法吗？

再次感谢大家!

Answer 1

如果您已经有一个 Rails 项目，您应该:

• 在您的 Gemfile 中指定所需的版本(例如 gem 'rails', '~> 5.2.0.rc1')
• 运行bundle install(可能需要bundle update)
• 运行 rails app:update(rake rails:update 用于 4.2 及更早版本)
• 按照屏幕上的说明进行操作
• 关注the official guide根据您的版本执行其他步骤