Module: CollectiveIdea::Acts::NestedSet

Defined in:
lib/awesome_nested_set/helper.rb,
lib/awesome_nested_set/awesome_nested_set.rb

Overview

:nodoc:

Defined Under Namespace

Modules: Columns, Helper, Model

Instance Method Summary collapse

Instance Method Details

#acts_as_nested_set(options = {}) ⇒ Object

Configuration options are:

  • :parent_column - specifies the column name to use for keeping the position integer (default: parent_id)

  • :left_column - column name for left boundry data, default “lft”

  • :right_column - column name for right boundry data, default “rgt”

  • :scope - restricts what is to be considered a list. Given a symbol, it’ll attach “_id” (if it hasn’t been already) and use that as the foreign key restriction. You can also pass an array to scope by multiple attributes. Example: acts_as_nested_set :scope => [:notable_id, :notable_type]

  • :dependent - behavior for cascading destroy. If set to :destroy, all the child objects are destroyed alongside this object by calling their destroy method. If set to :delete_all (default), all the child objects are deleted without calling their destroy method.

  • :counter_cache adds a counter cache for the number of children. defaults to false. Example: acts_as_nested_set :counter_cache => :children_count

See CollectiveIdea::Acts::NestedSet::Model::ClassMethods for a list of class methods and CollectiveIdea::Acts::NestedSet::Model::InstanceMethods for a list of instance methods added to acts_as_nested_set models



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# File 'lib/awesome_nested_set/awesome_nested_set.rb', line 41

def acts_as_nested_set(options = {})
  options = {
    :parent_column => 'parent_id',
    :left_column => 'lft',
    :right_column => 'rgt',
    :dependent => :delete_all, # or :destroy
    :counter_cache => false
  }.merge(options)

  if options[:scope].is_a?(Symbol) && options[:scope].to_s !~ /_id$/
    options[:scope] = "#{options[:scope]}_id".intern
  end

  write_inheritable_attribute :acts_as_nested_set_options, options
  class_inheritable_reader :acts_as_nested_set_options

  include CollectiveIdea::Acts::NestedSet::Model
  include Columns
  extend Columns

  belongs_to :parent, :class_name => self.base_class.to_s,
    :foreign_key => parent_column_name,
    :counter_cache => options[:counter_cache]
  has_many :children, :class_name => self.base_class.to_s,
    :foreign_key => parent_column_name, :order => quoted_left_column_name

  attr_accessor :skip_before_destroy

  # no bulk assignment
  if accessible_attributes.blank?
    attr_protected  left_column_name.intern, right_column_name.intern
  end

  before_create  :set_default_left_and_right
  before_save    :store_new_parent
  after_save     :move_to_new_parent
  before_destroy :destroy_descendants

  # no assignment to structure fields
  [left_column_name, right_column_name].each do |column|
    module_eval <<-"end_eval", __FILE__, __LINE__
      def #{column}=(x)
        raise ActiveRecord::ActiveRecordError, "Unauthorized assignment to #{column}: it's an internal field handled by acts_as_nested_set code, use move_to_* methods instead."
      end
    end_eval
  end

  scope :roots, where(parent_column_name => nil).order(quoted_left_column_name)
  scope :leaves, where("#{quoted_right_column_name} - #{quoted_left_column_name} = 1").order(quoted_left_column_name)

  define_callbacks :move, :terminator => "result == false"
end