Contents

module MptTree
  class Node < ActiveRecord::Base
    belongs_to :tree, :polymorphic=>true

    before_create :create_root_node
    before_destroy :delete_node

    def insert(node)
      Node.transaction do
        Node.where(:tree_type=>tree_type).where("rgt >= :rgt", :rgt=>self.rgt).update_all("rgt=rgt+2")
        Node.where(:tree_type=>tree_type).where("lft > :rgt", :rgt=>self.rgt).update_all("lft=lft+2")
        node.create_mpt_tree_node(:lft => self.rgt, :rgt=>self.rgt+1)
      end
    end

    def tree
      Node.where(:tree_type=>tree_type).where("lft > ? AND rgt < ?", self.lft, self.rgt ).order('lft').map(&:tree_id)
    end

    def ancestors
      Node.where(:tree_type=>tree_type).where("lft < ? AND rgt > ?", self.lft, self.rgt).order('lft').map(&:tree_id)
    end

    def leaf?
      self.rgt == self.lft+1
    end

    def level(parent=nil)
      sql = "lft < :self_lft AND rgt > :self_rgt "
      arguments = {:self_lft=>self.lft, :self_rgt=>self.rgt}
      if parent
        sql+= "AND lft >= :parent_lft AND rgt <= :parent_rgt"  
        arguments[:parent_lft]=parent.mpt_tree_node.lft; arguments[:parent_rgt]=parent.mpt_tree_node.rgt;
      end
      Node.where(:tree_type=>tree_type).where(sql, arguments).count(:id)
    end

    def self.root_created?(tree_type)
      !Node.where(:tree_type=>tree_type).empty?
    end

    private
      def delete_node
        allow_delete = false
        raise "the node you are trying to delete is not a leaf node!"  unless(self.leaf?)
        Node.where(:tree_type=>tree_type).where("lft > ?", self.rgt).update_all("lft = lft-2")
        Node.where(:tree_type=>tree_type).where("rgt > ?", self.rgt).update_all("rgt = rgt-2")
        allow_delete = true
        allow_delete
      end

      def create_root_node
        unless Node.root_created?(tree_type)
          self.lft, self.rgt = 1, 2  
        else
          raise "root node is already created" if self.lft == nil || self.rgt == nil
        end
      end

  end

end

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
mpt_tree-0.0.7	app/models/mpt_tree/node.rb