ruby-on-rails - 为什么我的 rails3 beta4 模型中出现 "SystemStackError: stack level too deep"

Question

在 ruby 1.9.2-rc1< 下的 rails3 beta4 中执行以下代码时，出现以下错误:SystemStackError: stack level too deep/:

ruby-1.9.2-rc1 > f = Forum.all.first
  => #<Forum id: 1, title: "Forum 1", description: "Description 1", content: "Content 1", parent_id: nil, user_id: 1, forum_type: "forum", created_at: "2010-07-17 04:39:41", updated_at: "2010-07-17 04:39:41", icon_file_name: nil, icon_content_type: nil, icon_file_size: nil, icon_updated_at: nil> 
ruby-1.9.2-rc1 > f.children
  => [#<Forum id: 2, title: "Thread 2", description: "Description 2", content: "Content 2", parent_id: 1, user_id: 1, forum_type: "thread", created_at: "2010-07-17 04:40:17", updated_at: "2010-07-17 04:40:17", icon_file_name: nil, icon_content_type: nil, icon_file_size: nil, icon_updated_at: nil>] 
ruby-1.9.2-rc1 > f.forum_type = "thread"
  => "thread" 
ruby-1.9.2-rc1 > f.save
SystemStackError: stack level too deep
from /Users/emilkampp/.rvm/rubies/ruby-1.9.2-rc1/lib/ruby/1.9.1/irb/workspace.rb:80
Maybe IRB bug!!
ruby-1.9.2-rc1 > 

这是由以下代码引起的:

# Before and after filters
# 
before_update :update_all_nested_objects, :if => :forum_type_changed?

protected
  # Checks if the +forum_type+ has been changed
  # 
  def forum_type_changed?
    self.forum_type_changed?
  end

  # Updates all nested upjects if the +forum_type+ has been changed
  # 
  # This will trigger the +update_all_nested_objects+ method on all touched children, thus 
  # starting a chain-reaction all the way through the forum-tree.
  # 
  # NOTE: This is where the error is triggered, since this is the only non-tested looping code, and my test-
  #       cases hasn't changed since this was added.
  # 
  def update_all_nested_objects
    children.each do |child|
      child.forum_type = child_type
      child.save
    end
  end

所以，这是怎么回事。我一直在检查周围，但似乎没有人遇到同样的问题。不是相同的 ruby​​ 版本，因此 workflow.rb 文件不同，或者 stack level to deep 是由其他原因引起的。

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//埃米尔

Answer 1

你在方法本身调用相同的方法

  def forum_type_changed?
    self.forum_type_changed?  #This will never ending process hence it gives error
  end

我认为你有相同的 method name 和 column name 导致问题然后更改你的方法名称

  def check_forum_type_changed?
    self.forum_type_changed?  #method name and column name are different
  end