不建议全局访问 Rake DSL 方法

我正在阅读 Ruby on Rails 3教程，并在命令行中输入了以下内容:

rake db:migrate

产生以下警告。

WARNING: Global access to Rake DSL methods is deprecated.  Please Include
...  Rake::DSL into classes and modules which use the Rake DSL methods.


WARNING: DSL method DemoApp::Application#task called at /Users/imac/.rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/railties-3.0.7/lib/rails/application.rb:215:in `initialize_tasks'

我不知道该怎么办，也不知道如何应对。我不知道雷克还有什么指挥官。

我怎样才能解决这个问题？

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最佳答案

I found this in Stack Overflow question Ruby on Rails and Rake problems: uninitialized constant Rake::DSL. It refers to a @DHH tweet.

Put the following in your Gemfile

gem "rake", "0.8.7"

You may see something like 

rake aborted!
You have already activated Rake 0.9.1 ...

I still had a copy of Rake 0.9.1 in my directory so I deleted it.

You can "delete" Rake 0.9.1 by running the following command: 

gem uninstall rake -v=0.9.1

If you have multiple versions of the gem installed, you'll be prompted to pick a version.

After 0.9.1 was cleaned out, I ran 

bundle update rake

and was finally able to create my database files. I was using rake db:create, but it should work for rake db:migrate as well.

I hope it helps.

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Adding include Rake::DSL to the Rakefile before the applications load_tasks were called also worked for me.

So in the above user's case before the DemoApp::Application.load_tasks in the Rakefile.

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I was having the same problem on Windows with the installer. Ruby 1.9.2 and Rails 3.0.9. Here is what I did:

bundle update rake
bundle show rake

After doing that I was running rake 0.9.2.

Then I updated the Rakefile in application root folder as follows:

require File.expand_path('../config/application', __FILE__)
require 'rake'
# If you named your application something other than SampleApp, change that below
module ::SampleApp
class Application
include Rake::DSL
end
end


module ::RakeFileUtils
extend Rake::FileUtilsExt
end


SampleApp::Application.load_tasks

As noted in the comment, make sure the name of your app is correct in the two appropriate lines above.

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If you are seeing this on later versions of Rails (like 3.+) you may also want to verify that your environment is clean by using RVM http://beginrescueend.com/ and creating a specific ruby & gemset for your projects.

Use an .rvmrc file on a per-project basis, this will guarantee you aren't getting older system gems into your projects. Which has bitten me before.

This prevents having to monkey around with generated Rakefiles & such.

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bundle exec rake db:migrate will solve your ruby version issues


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