Why am I getting a "SystemStackError: stack level too deep" in my rails3 beta4 model

Question

I'm getting the following error: SystemStackError: stack level too deep when executing the following code in rails3 beta4 under ruby 1.9.2-rc1:

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 > 

And that is caused by the following code:

# 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

So, what's going on. I have been checking around a little, but nobody seems to have the same problem. Either it's not the same ruby version, thus the workflow.rb file is different, or the stack level to deep is caused by something else.

Any help will be greatly apreciated!

Best regards

// Emil

Answer 1

You are calling same method in method itself

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

I think you have same method name and column name that causing problem change your method name then

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