yaml, activerecord and acts_as_nested_set

Geoffrey — Sun, 02 Dec 2007 16:41:00 +0100

I used to use this yaml_to_ar lib from christophe to load categories tree into my database, using acts_as_tree in the model that was perfect. Arrived the time when I felt the need to use acts_as_nested_set instead, for which I had to fill the lft and rgt columns. So I just rewrote the yaml_to_ar piece of code (put this in lib/yaml_to_ar.rb):

require 'yaml'



class YAML_to_AR



  def initialize(file, model)

    @data = File.open(file) { |yf| YAML::load( yf ) }

    @model = model

  end



  def process(data = @data, parent = nil)

    if data.is_a? Array

      data.each do |val|

        process(val, parent)

      end

    elsif data.is_a? Hash

      data.each do |key,val|

        parent = @model.create(:title => key)

        process(val, parent)

      end

    elsif data.is_a? String

      parent.add_child(@model.create(:title => data))

    end

  end



 end

This should handle both acts_as_tree and acts_as_nested. To ease things a bit further, I also wrote a rake task (to drop in lib/tasks/db_load_categories.rake for example):

namespace :db do

  desc "Loads categories defaults data"

  task :load_categories => :environment do

    require 'lib/yaml_to_ar'

    Category.delete_all

    categories = YAML_to_AR.new('db/categories.yml', Category)

    categories.process

  end

end

Now I just rake db:load_categories, and voila !

Mirmo Dynamics - Tag - activerecord

yaml, activerecord and acts_as_nested_set