Mongodb/mongoid rails 项目——“在第 8 行第 7 列解析块映射时没有找到预期的键（Psych::SyntaxError）”答案

【问题标题】：Mongodb/mongoid rails project -- "did not find expected key while parsing a block mapping at line 8 column 7 (Psych::SyntaxError)"Mongodb/mongoid rails 项目——“在第 8 行第 7 列解析块映射时没有找到预期的键（Psych::SyntaxError）”
【发布时间】：2016-09-09 02:49:42
【问题描述】：

我有一个使用 mongodb/mongoid 和一些额外的 mongodb/mongoid gems 的 rails 项目：

ruby "2.3.1"
gem 'rails', '4.1.1'
gem 'mongoid'

当我尝试运行它时，我得到一个异常：

$ bundle exec rails s
/home/alex/.gem/ruby/2.3.1/gems/activesupport-4.1.1/lib/active_support/values/time_zone.rb:285: warning: circular argument reference - now
=> Booting Thin
=> Rails 4.1.1 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Notice: server is listening on all interfaces (0.0.0.0). Consider using 127.0.0.1 (--binding option)
=> Ctrl-C to shutdown server
Exiting
/home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:377:in `parse': (<unknown>): did not find expected key while parsing a block mapping at line 8 column 7 (Psych::SyntaxError)
        from /home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/psych.rb:377:in `parse_stream'
        from /home/alex/.gem/ruby/2.3.1/gems/mongoid-4.0.2/lib/mongoid/config/environment.rb:40:in `load_yaml'
        from /home/alex/.gem/ruby/2.3.1/gems/mongoid-4.0.2/lib/mongoid/config.rb:83:in `load!'
        # ............skipped
        from /home/alex/.gem/ruby/2.3.1/gems/railties-4.1.1/lib/rails/initializable.rb:55:in `block in run_initializers'
        from /home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
        from /home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
        from /home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
        from /home/alex/.rubies/ruby-2.3.1/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
        # .......... skipped
        from /home/alex/.gem/ruby/2.3.1/gems/activesupport-4.1.1/lib/active_support/dependencies.rb:232:in `load_dependency'
        from /home/alex/.gem/ruby/2.3.1/gems/activesupport-4.1.1/lib/active_support/dependencies.rb:247:in `require'
        from /home/alex/projects/ruby/my_project_123/config.ru:3:in `block in <main>'
        from /home/alex/.gem/ruby/2.3.1/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
        # ............skipped
        from /home/alex/.gem/ruby/2.3.1/gems/railties-4.1.1/lib/rails/commands.rb:17:in `<top (required)>'
        from bin/rails:4:in `require'
        from bin/rails:4:in `<main>'

什么会导致这个异常？

【问题讨论】：

标签： ruby-on-rails ruby mongodb mongoid

【解决方案1】：

Psych 是一个 YAML 解析器和发射器。该错误表明在您的 yml 文件中某个键值之前有多余的空格（或没有足够的空格）。检查所有 yml 文件（例如：mongoid.yml）的语法是否正确。您可以验证您的 yml 文件 Here。例如在下面的 YAML 中

key_one:
  inner:
  - value1
  - value2

key_two:
    inner:
  - value1
  - value2

第 7 行第 5 列在键值之前有一个额外的空格

【讨论】：