POS-Server/app/models/category.rb

class Category < ActiveRecord::Base
	##--- Associaciones
	has_and_belongs_to_many :products
	belongs_to :parent, :class_name => "Category"
  has_many :children, -> { where "status!= 0" }, :class_name => "Category", :foreign_key => 'parent_id'

	enum status: [ :erased, :active, :inactive ]

  ##--- Llevar registro de Actividad del usuario
  audited

	##--- Validaciones previas de guardar
	validates :category , presence: { message: "Debe capturar el nombre de la línea de producto." }

	##--- Tipo de vistas / consultas
	scope :vigentes, -> { where( "status != 0").order(" status ASC, category ASC") }
	scope :activos, -> { where( "status = 1").order(" category ASC") }
	scope :activos_padre, -> { where( "status = 1 AND parent_id = 0").order(" category ASC") }
	scope :get_parents, -> { where( "parent_id = 0 and status != 0").order(" category ASC") }

  def descendents
    self_and_descendents - [self]
  end

  def self_and_descendents
    self.class.tree_for(self)
  end

  def self.tree_for(instance)
    where("#{table_name}.id IN (#{tree_sql_for(instance)})").order("#{table_name}.id")
  end

  def self.tree_sql_for(instance)
    tree_sql =  <<-SQL
      WITH RECURSIVE search_tree(id, path) AS (
          SELECT id, ARRAY[id]
          FROM #{table_name}
          WHERE id = #{instance.id}
        UNION ALL
          SELECT #{table_name}.id, path || #{table_name}.id
          FROM search_tree
          JOIN #{table_name} ON #{table_name}.parent_id = search_tree.id
          WHERE NOT #{table_name}.id = ANY(path)
      )
      SELECT id FROM search_tree ORDER BY path
    SQL
  end

	protected

		before_save  do
			self.parent_id = 0 if parent_id.nil?
		end

end