Rails - Apr 2005 - before_destroy callback / maintaining referential integrity

Greets all,

I''m pullin my hair out over something that I thought would be a piece
of cake (and probably is). I''m trying to prevent a record from being
destroyed if it is still referenced in another table. If it is
referenced, I just want to add a message to flash or errors. I have:

class Arrival < ActiveRecord::Base
  belongs_to :vessel_type
  validates_length_of :vessel, :within => 1..64
end

class VesselType < ActiveRecord::Base
  has_one :arrival
  validates_length_of :name, :within => 1..64
  validates_uniqueness_of :name, :message => "already exists"
  before_destroy :check_in_use

  protected
    def check_in_use
      # insert many attempts here
    end
end

Any tips or insight are gratefully appreciated. Please let me know if
I can provide additional information.

Thanks,

John

> I''m pullin my hair out over something that I thought would be a
piece
> of cake (and probably is). I''m trying to prevent a record from
being
> destroyed if it is still referenced in another table. If it is
> referenced, I just want to add a message to flash or errors. I have:
You need to raise an exception in an before_destroy filter to stop the 
destruction from happening. The validations doesn''t really have 
anything to do with that. Validations are only something that govern 
saves (create/update).
--
David Heinemeier Hansson,
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