Rails - Jun 2007 - acts_as_tree and before_save

We all know that acts_as_tree gives us ability to set up data in a
tree-like structure and use methods like ''parent'',
''children'' and so on.

Something I''m completely stuck on. Observe.

class Page < ActiveRecord::Base
  acts_as_tree

  def before_save
    raise self.parent.to_yaml
  end
end

Well, you''d think that it should show element''s parent element
but for
some reason it''s always blank.

Why don''t I have access to parent element here? Parent method seems to
work just fine when I actually save the thing. So child_element
element.children.create(blahblah) and child_element.parent gives me the
parent element as it suppose to.

What am I missing here?

Thanks.

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>   def before_save
>     raise self.parent.to_yaml
>   end
> end
> 
> Why don''t I have access to parent element here? Parent method
seems to
> work just fine when I actually save the thing. So child_element >
element.children.create(blahblah) and child_element.parent gives me the
> parent element as it suppose to.
> 
it doesn''t work, because raise makes it not work. raise is:

http://www.rubycentral.com/book/ref_m_kernel.html#Kernel.raise

it raises an exception; maybe you''re looking for render or some other 
method, but if i''m getting your drift (maybe i''m missing it
entirely)
raise is not what you''re looking for.

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> it doesn''t work, because raise makes it not work. raise is:
> 
> http://www.rubycentral.com/book/ref_m_kernel.html#Kernel.raise
> 
> it raises an exception; maybe you''re looking for render or some
other
> method, but if i''m getting your drift (maybe i''m missing
it entirely)
> raise is not what you''re looking for.
I know what raise does. Point is that at that stage it should error out 
and show me contents of the parent element. In my case it''s always nil 
because self.parent is nil, instead of being a Page object.

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> I know what raise does. 
sorry ''bout that. didn''t mean to bring it along that way ... 
:)
> and show me contents of the parent element. In my case it''s always
nil
> because self.parent is nil, instead of being a Page object.
...what happens if you do it in an after_save call? a small guess would 
be it wouldn''t work on a before_save :on => create (whereas :on
=>
update would work) because the new record doesn''t actually exist in the
db when the before_save is called. if i am correct, the child.parent 
method actually goes to the db to check the parent_id column, and the 
before_save is called before the actual writing to the db.

...?

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