Module: EvenBetterNestedSet

Defined in:
lib/eb_nested_set.rb

Defined Under Namespace

Modules: NestedSet Classes: IllegalAssignmentError, NestedSetError

Instance Method Summary collapse

Instance Method Details

#acts_as_nested_set(options = {}) ⇒ Object

Declare this model as a nested set. Automatically adds all methods in EvenBetterNestedSet::NestedSet to the model, as well as parent and children associations.

Options

left [Symbol]

the name of the column that contains the left boundary [Defaults to left]

right [Symbol]

the name of the column that contains the right boundary [Defaults to right]

scope [Symbol]

the name of an association to scope this nested set to

Parameters:

  • options (Hash) (defaults to: {}) —

    a set of options



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# File 'lib/eb_nested_set.rb', line 18

def acts_as_nested_set(options={})
  options = { :left => :left, :right => :right }.merge!(options)
  options[:scope] = "#{options[:scope]}_id" if options[:scope]

  include NestedSet

  self.nested_set_options = options

  class_eval <<-RUBY, __FILE__, __LINE__+1
    def #{options[:left]}=(left)
      raise EvenBetterNestedSet::IllegalAssignmentError, "#{options[:left]} is an internal attribute used by EvenBetterNestedSet, do not assign it directly as is may corrupt the data in your database"
    end

    def #{options[:right]}=(right)
      raise EvenBetterNestedSet::IllegalAssignmentError, "#{options[:right]} is an internal attribute used by EvenBetterNestedSet, do not assign it directly as is may corrupt the data in your database"
    end
  RUBY

  named_scope :roots, :conditions => { :parent_id => nil }, :order => "#{nested_set_column(:left)} asc"
  has_many :children, :class_name => self.name, :foreign_key => :parent_id, :order => "#{nested_set_column(:left)} asc"
  belongs_to :parent, :class_name => self.name, :foreign_key => :parent_id

  named_scope :descendants, lambda { |node|
    left, right = find_boundaries(node.id)
    { :conditions => ["#{nested_set_column(:left)} > ? and #{nested_set_column(:right)} < ?", left, right],
      :order => "#{nested_set_column(:left)} asc" }
  }

  before_create :append_node
  before_update :move_node
  before_destroy :reload
  after_destroy :remove_node
  validate_on_update :illegal_nesting
  validate :validate_parent_is_within_scope

  delegate :nested_set_column, :to => "self.class"
end