我正在尝试设置我的开发环境以使用正在使用Mongoid的现有项目。我已经运行了bundle install并且工作正常，但我现在正在尝试设置数据库，而我正在运行rake db:setup
这是输出：
[1] $ rake db:setup --trace ✘
** Invoke db:setup (first_time)
** Invoke db:create (first_time)
** Invoke environment (first_time)
** Execute environment
rake aborted!
You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.+
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/bundler/gems/cantango-36e3ce152717/lib/cantango/configuration/registry.rb:31:in `register'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/bundler/gems/cantango-36e3ce152717/lib/cantango/configuration/candidate_registry.rb:10:in `register'
/home/chintanparikh/Documents/Work/project_name/config/initializers/cantango.rb:8:in `block in <top (required)>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/bundler/gems/cantango-36e3ce152717/lib/cantango.rb:23:in `configure'
/home/chintanparikh/Documents/Work/project_name/config/initializers/cantango.rb:2:in `<top (required)>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:234:in `load'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:234:in `block in load'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `block in load_dependency'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:640:in `new_constants_in'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `load_dependency'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:234:in `load'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/engine.rb:556:in `block (2 levels) in <class:Engine>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/engine.rb:555:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/engine.rb:555:in `block in <class:Engine>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/initializable.rb:30:in `instance_exec'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/initializable.rb:30:in `run'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/initializable.rb:55:in `block in run_initializers'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/initializable.rb:54:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/initializable.rb:54:in `run_initializers'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/application.rb:96:in `initialize!'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/railtie/configurable.rb:30:in `method_missing'
/home/chintanparikh/Documents/Work/project_name/config/environment.rb:5:in `<top (required)>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `require'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `block in require'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `block in load_dependency'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:640:in `new_constants_in'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:223:in `load_dependency'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/activesupport-3.1.3/lib/active_support/dependencies.rb:240:in `require'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/application.rb:83:in `require_environment!'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0/gems/railties-3.1.3/lib/rails/application.rb:193:in `block (2 levels) in initialize_tasks'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:227:in `call'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:227:in `block in execute'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:222:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:222:in `execute'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:166:in `block in invoke_with_call_chain'
/home/chintanparikh/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:187:in `block in invoke_prerequisites'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:185:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:185:in `invoke_prerequisites'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:165:in `block in invoke_with_call_chain'
/home/chintanparikh/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:187:in `block in invoke_prerequisites'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:185:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:185:in `invoke_prerequisites'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:165:in `block in invoke_with_call_chain'
/home/chintanparikh/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:159:in `invoke_with_call_chain'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/task.rb:152:in `invoke'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:141:in `invoke_task'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:99:in `block (2 levels) in top_level'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:99:in `each'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:99:in `block in top_level'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:108:in `run_with_threads'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:93:in `top_level'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:71:in `block in run'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:158:in `standard_exception_handling'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/lib/rake/application.rb:68:in `run'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/gems/rake-10.0.1/bin/rake:37:in `<top (required)>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/bin/rake:19:in `load'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/bin/rake:19:in `<main>'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/bin/ruby_noexec_wrapper:14:in `eval'
/home/chintanparikh/.rvm/gems/ruby-1.9.3-p0@global/bin/ruby_noexec_wrapper:14:in `<main>'
Tasks: TOP => db:setup => db:create => environment
有谁知道如何解决这个问题？看起来它在创建步骤上失败了。
干杯。
答案 0 :(得分：3)
MongoDB是一个无模式数据库。您不需要使用任何rake db:{}函数。启动和运行mongodb所需要做的唯一事情就是安装它然后启动服务器。您可以找到有关安装MongoDB here