ruby datamapper 不会加载

Question

我试图按照本教程学习 Sinatra ruby​​ 框架:

http://net.tutsplus.com/tutorials/ruby/singing-with-sinatra-the-recall-app-2/

但是，在运行 gem 安装并在 test.rb 中编写一个简单的 sinatra 服务器后，如下所示:

require 'sinatra'
require 'datamapper'

get '/' do 
  "Hello, World!"
end

但是当我运行命令 ruby test.rb 时，出现以下错误:

/usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': no such file to load -- datamapper (LoadError)
    from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from datamapper_test.rb:2:in `<main>'
glenn@ubuntu:~/Dropbox/Repositories/sandbox/sinatra$ ruby datamapper_test.rb 
/usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': no such file to load -- datamapper (LoadError)
    from /usr/local/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
    from test.rb:3:in `<main>'

它似乎找不到数据映射器 gem。我该如何解决这个问题？

编辑:使用 ruby​​ 1.9.2

编辑(再次):gem list 的(部分)输出:

data_mapper (1.2.0)
data_objects (0.10.8)
datamapper (1.2.0)
devise (1.4.5)
directory_watcher (1.4.0)
dm-aggregates (1.2.0)
dm-constraints (1.2.0)
dm-core (1.2.0)
dm-do-adapter (1.2.0)
dm-migrations (1.2.0)
dm-serializer (1.2.1)
dm-sqlite-adapter (1.2.0)
d    m-timestamps (1.2.0)
dm-transactions (1.2.0)
dm-types (1.2.1)
dm-validations (1.2.0)
do_sqlite3 (0.10.8)
sinatra (1.3.2, 1.2.6)
sqlite3 (1.3.5, 1.3.4)
sqlite3-ruby (1.3.3)

Answer 1

您需要需要'data_mapper'，而不是datamapper。

请注意，有一个 datamapper gem 和一个 data_mapper gem，但它们是相同的东西，只是名称不同。您需要使用 data_mapper 作为它们中的库名称。

据我所知，datamapper 是 data_mapper 的直接副本:

$ diff -r data_mapper-1.2.0/ datamapper-1.2.0/
diff -r data_mapper-1.2.0/Rakefile datamapper-1.2.0/Rakefile
21c21
< GEM_NAME         = 'data_mapper'
---
> GEM_NAME         = 'datamapper'