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ruby script/generate model Outline

exists  app/models/
exists  test/unit/
exists  test/fixtures/
create  app/models/outline.rb
create  test/unit/outline_test.rb
create  test/fixtures/outlines.yml
create  db/migrate
create  db/migrate/001_create_outlines.rb

class CreateOutlines < ActiveRecord::Migration
  def self.up
    create_table :outlines do |t|
      t.column :parent_id,      :integer
      t.column :name,           :string, :null => false
      t.column :position,       :integer, :null => false
    end
  end

  def self.down
    drop_table :outlines
  end
end

rake db:migrate

class Outline < ActiveRecord::Base
  acts_as_list  :scope => :parent_id
  acts_as_tree  :order => "position"
end

#testing of the list features
o1 = Outline.new :name => "first" #create an instance with name "first"
=> #...
o1.save!
=> true
o1.position #its position is 1
=> 1
o2 = Outline.new :name => "second" #create another instance with name "second"
=> #...
o2.save!
=> true
o2.position #its position is 2
=> 2
o2.move_higher #move second item higher
=> true
o2.position #it is on the top; its position is 1
=> 1
o1.reload #it is necessary to reload it to reflect the previous change
=> #...
o1.position
=> 2

#testing of the tree features
o11 = Outline.new :name => "first's child" #let's create a child
=> #...
o1.children << o11 #assign it to its parent
=> [#...]
o11.position #the position is 1, because it is the first child of "first"
=> 1
>> o11.parent.name #what is the parents name? should be "first"
=> "first"
>> o1.children.each do |c| puts c.name end #what are the children names?
first's child
=> [#...]

class Outline < ActiveRecord::Base
  belongs_to    :parent,
                :class_name => "Outline"

  acts_as_list  :scope => :parent_id

  has_many      :children,
                :class_name  => "Outline",
                :foreign_key => "parent_id",
                :order       => "position",
                :dependent   => :destroy

  acts_as_tree  :order       => "position"
end