所以RHEL5和OSX Lion上都出现了这个问题。两个环境都运行随RVM安装的1.9.2-p290 ruby。
当我运行以下命令时，我遇到以下问题：
[master][~/Sites/boss-mocha] bundle exec rake db:data:load --trace
** Invoke db:data:load (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute db:data:load
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.each
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/serialization_helper.rb:85:in `load_records'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/serialization_helper.rb:74:in `load_table'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/yaml_db.rb:63:in `block (2 levels) in load_documents'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/yaml_db.rb:61:in `each'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/yaml_db.rb:61:in `block in load_documents'
/Users/pma/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/deprecated.rb:30:in `each'
/Users/pma/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych/deprecated.rb:30:in `load_documents'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/yaml_db.rb:60:in `load_documents'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/serialization_helper.rb:57:in `block in load'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.0.10/lib/active_record/connection_adapters/abstract/database_statements.rb:139:in `transaction'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/serialization_helper.rb:56:in `load'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/serialization_helper.rb:31:in `load'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/yaml_db-0.2.1/lib/tasks/yaml_db_tasks.rake:35:in `block (3 levels) in <top (required)>'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:205:in `call'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:205:in `block in execute'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:200:in `each'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:200:in `execute'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:158:in `block in invoke_with_call_chain'
/Users/pma/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/monitor.rb:201:in `mon_synchronize'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:151:in `invoke_with_call_chain'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/task.rb:144:in `invoke'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:112:in `invoke_task'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:90:in `block (2 levels) in top_level'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:90:in `each'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:90:in `block in top_level'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:84:in `top_level'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:62:in `block in run'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:129:in `standard_exception_handling'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/lib/rake/application.rb:59:in `run'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/gems/rake-0.9.2/bin/rake:32:in `<top (required)>'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/bin/rake:19:in `load'
/Users/pma/.rvm/gems/ruby-1.9.2-p290/bin/rake:19:in `<main>'
Tasks: TOP => db:data:load
答案 0 :(得分：0)
由rake db：data：dump生成的YAML看起来格式不正确，“记录”列表与实际记录之间存在虚假的“---”。
删除不合适的“---”可以加载数据。我还没有为修复程序创建拉取请求，但在跟踪它之后我注意到有人在github上报告了它是一个问题：
https://github.com/ludicast/yaml_db/issues/17
此外，如下面的链接更改YAML引擎会产生正确的输出，无需手动编辑文件（或修复yaml_db）。