Rails 3的“捆绑安装”速度超快（需要1秒），但之后没有Rails吗？ （使用rvm）

Question

I am using rvm, doing the following:

rvm install ree    <--- (Ruby Enterprise Edition), or this can be 1.8.7 or 1.9.2
rvm ree
rvm gemset create 'proj'
cd path/to/proj
bundle install

so Gemfile in that project says:

gem 'rails', '3.0.0'

and bundle install is super fast, reporting

Using rails (3.0.0) 

but after that when I type

$ rails -v
/Library/Ruby/Site/1.8/rubygems.rb:779:in `report_activate_error': Could not find RubyGem rails (>= 0) (Gem::LoadError)
    from /Library/Ruby/Site/1.8/rubygems.rb:214:in `activate'
    from /Library/Ruby/Site/1.8/rubygems.rb:1082:in `gem'
    from /usr/bin/rails:18

$ which rails
/usr/bin/rails

so bundle install doesn't install the rails as a gem? but if I type script/rails -v it shows it is 3.0.0

Answer 1

This is correct. bundle install won't install Rails as a gem in the conventional sense. Now to explain why.

When Bundler runs an install, it will install the gems a directory: ~/.bundle/<type-of-ruby>/<version>/gems . This is different to the normal way of installing them to a system path. When a gem is installed at a system path, the executable is made available because that directory is within the load path. Now this is a bad thing, because you can only have one executable per gem . Have you got SomeGem v2 installed but want to use the generator from SomeGem v1? Too bad.

Bundler solves this problem by installing them into the afore-mentioned location and only requiring specific versions of the gems it needs (specified inside of Gemfile . By running simply rails , you're trying to run the system executable (as in one provided by doing gem install rails ) rather than the Bundler one (provided by doing bundle install for a Rails project).

To run the one that Bundler installs you must run it like this bundle exec rails within a directory that contains a Gemfile that specifies any version of Rails. Bundler will load a specific version of Rails and you should now be able to run them side-by-side with the only tradeoff being the bundle exec prefix to commands.

Personally I've aliased this to be and two characters before some commands is a worthwhile tradeoff to avoiding The Seventh Circle of Gem Conflict Hell in my opinion.

Answer 2

your procedure seems correct (be sure to use the newly created gemset too, verify by rvm info , do rvm ree@proj if it doesn't say gemset: 'proj' ), so I'll stick my head out and try a suggestion. Btw, rails installs perfectly with bundler.

I've been struggling with wierd behaviour system gems vs local gems, as have a lot of bundler users, including Yehuda Katz, leading to this comprehensive post A Tale of Abort Traps

In short, if you run bundle install before you have the bundler gem (getting the "standard" gem not found error), then do gem install bundler , followed by another bundle install, the bundler gem has been install to your system, not rvm .

Solution : Delete .bundle, (and do gem uninstall bundler?). Then I would open a new term, do rvm ree@proj, and gem install bundler prior to bundle install.

Yehuda says in the post that it is fixed in new bundler versions, but I experienced this just a few days ago (bundler 1.0.0). Hope I brought more help than confusion to the table :)