AASM 不适用于我的 rails 3 和 ruby 1.8.7（nil:NilClass 的未定义方法“名称”）答案

【问题标题】：AASM is not working with my rails 3 and ruby 1.8.7 ( undefined method `name' for nil:NilClass )AASM 不适用于我的 rails 3 和 ruby 1.8.7（nil:NilClass 的未定义方法“名称”）
【发布时间】：2012-06-16 20:07:23
【问题描述】：

我正在使用带有 aasm gem 的 Rails 3.2.2，我有 Document 这样的模型：

class Document < ActiveRecord::Base
  include AASM

  aasm do  
    state :unread, :initial => true
    state :read
    state :closed

    event :view do
      transitions :to => :read, :from => [:unread]
    end

    event :close do
      transitions :to => :closed, :from => [:read, :unread]
    end
  end

现在在我的控制台上：

➜  ✗ bundle exec rails c
Loading development environment (Rails 3.2.2)
irb(main):006:0> Document.create!(:title => 'test')
   (0.2ms)  BEGIN
  SQL (0.3ms)  INSERT INTO `documents` (`aasm_state`, `checklist_id`, `created_at`, `description`, `dir`, `planned_date`, `procedure_id`, `section`, `subsection`, `title`, `updated_at`) VALUES (0, NULL, '2012-06-16 20:03:18', NULL, NULL, NULL, NULL, NULL, NULL, 'test', '2012-06-16 20:03:18')
   (0.4ms)  COMMIT
=> #<Document id: 28, title: "test", description: nil, dir: nil, section: nil, subsection: nil, planned_date: nil, procedure_id: nil, checklist_id: nil, created_at: "2012-06-16 20:03:18", updated_at: "2012-06-16 20:03:18", aasm_state: 0>
irb(main):007:0> doc = Document.last
  Document Load (0.3ms)  SELECT `documents`.* FROM `documents` ORDER BY `documents`.`id` DESC LIMIT 1
=> #<Document id: 28, title: "test", description: nil, dir: nil, section: nil, subsection: nil, planned_date: nil, procedure_id: nil, checklist_id: nil, created_at: "2012-06-16 20:03:18", updated_at: "2012-06-16 20:03:18", aasm_state: 0>
irb(main):008:0> doc.view!
NoMethodError: undefined method `name' for nil:NilClass
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/supporting_classes/state.rb:15:in `=='
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/aasm.rb:143:in `aasm_state_object_for_state'
    from (irb):8:in `find'
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/aasm.rb:143:in `each'
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/aasm.rb:143:in `find'
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/aasm.rb:143:in `aasm_state_object_for_state'
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/aasm.rb:158:in `aasm_fire_event'
    from /Library/Ruby/Gems/1.8/gems/aasm-3.0.6/lib/aasm/base.rb:48:in `view!'
    from (irb):8

如你所见，我不断得到

nil:NilClass 的未定义方法“名称”

我使用的是 Ruby 1.8.7。

【问题讨论】：

您是如何创建 aasm 列“aasm_state”的？（你的数据库模式是什么样子的？）可能是你使用了列类型整数吗？确保使用 字符串。 :)

标签： ruby-on-rails ruby ruby-on-rails-3 ruby-1.8.7 aasm

【解决方案1】：

我也遇到了同样的问题。它的出现是因为默认状态变量是nil，而不是设置为初始状态。要解决此问题，在您的情况下，您需要在模型上添加一个访问器，如下所示：

def aasm_state
  self[:aasm_state] || "unread"
end

【讨论】：

【解决方案2】：

需要写出准确的列名。

aasm column: :aasm_state do 
end

【讨论】：