snippet.rb

puts `ruby -v`
require 'rubygems'
require 'active_support'
require 'dm-core'
require 'dm-sqlite-adapter'
require 'data_mapper'
require 'dm-is-list'
require 'dm-is-tree'

class Album
  include DataMapper::Resource
  property :id, Serial
  property :parent_id,              Integer
  property :name,                   String,   :length => 150 
  property :description,            Text,     :default => "", :lazy => false 
  property :url_slug,               String,   :length => 255
  property :created_at,             DateTime
  property :updated_at,             DateTime
  
  
  is :list, :scope => [:parent_id]
  # is :tree, :order => [:parent_id, :position]
  
  before :valid?,   :set_default_values_if_missing
  
  before :save do |album|
    puts "SAVING ALBUM album=[#{album.inspect}]"
  end
  
  before :destroy do |album|
    puts "DESTROYING Album=[#{album.inspect}]\n"
  end
  
  protected
    
    # update all the records with the new parent id
    def unlink_from_parent! 
      self.class.all(:parent_id => self.parent_id).update(:parent_id => self.parent.parent.id || nil )
    end
    def set_default_values_if_missing
      self.parent_id = nil if self.parent_id.blank?
    end
end


DataMapper.setup :default, 'sqlite3::memory:'
DataMapper::Logger.new(STDOUT, :debug)
DataMapper.logger.debug "Using DataMapper::VERSION=[#{DataMapper::VERSION}]"

DataMapper.auto_migrate!

puts "\n======= CREATING ALBUMS ======="
m = Album.create(:name => "Album", :description => 'Album Album', :url_slug => "archive")
ac1 = Album.create(:parent_id => m.id, :name => "Album|Child1", :description => 'Album Child1 Album', :url_slug => "album|child1")
ac2 = Album.create(:parent_id => m.id, :name => "Album|Child2", :description => 'Album Child2 Album', :url_slug => "album|child2")
puts "====== /CREATING ALBUMS ======\n\n"

puts "======== ALL ALBUMS ========="
Album.all.each { |a| puts a.inspect }
puts "======== /ALL ALBUMS ========\n\n"


puts "======== B4 DESTROY ========="
m.destroy
puts "======= /AFTER DESTROY ======\n\n"

puts "======== ALL ALBUMS ========="
Album.all.each { |a| puts a.inspect }
puts "======== /ALL ALBUMS ========\n\n"

DataMaper BUG ?? dm-is-tree and before :destroy callbacks

The above code outputs the before :destroy callback because the [ is :tree,... ] is commented out.

Once I uncomment it, the before :destroy callback stops working.

What am I doing wrong ?