Mongoid Set Defaults Rake Task

gistfile1.rb

require 'config/environment'
require 'mongo'

namespace :mongoid do
  desc 'Update defaults'
  task :defaults do
    db = Mongoid.config.master
    
    models.each do |m|
      m = eval m
      if !m.embedded?
        fields_with_defaults = m.fields.select {|k,v| v.options.include?(:default)}
        fields_with_defaults.each do |f|
          field_name = f[0]
          default_value = f[1].options[:default]
          field_type = f[1].options[:type]
          if valid_mongo_type(field_type)
            result = db.collection(m.collection.name).update({field_name => {'$exists' => false}}, {'$set' => {field_name => default_value}}, :multi => true, :safe => true)
            puts result
          end
        end
      end
    end
  end
end

def models 
  Module.constants.select do |constant_name|
    constant = eval constant_name
    if not constant.nil? and constant.is_a? Class and constant.included_modules.include? Mongoid::Document
      constant
    end
  end
end

def valid_mongo_type(t)
  [Array, BigDecimal, Boolean, Date, DateTime, Float, Hash, Integer, String, Symbol, Time, BSON::ObjectId].include?(t)
end