Question

I am trying to generate xml file as a background task using resque gem here is the class which generates xml file ….

ENV['RAILS_ENV'] = ARGV.first || ENV['RAILS_ENV']
require File.expand_path(File.dirname(__FILE__) + "/../../config/environment")
require  'rubygems'
require 'builder'

class GenerateXml
  @queue = :worker

  def self.perform
    file_name = "#{Time.now.strftime('%Y_%m_%d')}_export.xml"

    xml = Builder::XmlMarkup.new(:target => file_name, :indent => 2)
    xml.instruct!(:xml, :encoding => "UTF-8")

    xml.Postings do
      Result.find_in_batches do |result|
        xml.Posting do
          xml.JobID result.job_id
          xml.JobURL result.job_url
        end
      end
    end
  end
end

and my result model from where I am extracting the fields for the xml tags is like this

require 'active_record'

class Result < ActiveRecord::Base
  def job_id
    self.link
  end

  def job_url
    self.link
  end
end

My question is why result.job_url and result.job_id from class GenerateXml is not able to map to Result class correctly?

and one more thing the Result class is under app/models directory where as GenerateXml class is under lib/jobs directory

Here is the trace of error.

      undefined method `job_id' for #<Array:0xb3f26738>

/home/netserv/RubymineProjects/crawler/lib/jobs/generate_xml.rb:22:in `perform'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:155:in `call'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:155:in `_nested_structures'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:63:in `method_missing'
/home/netserv/RubymineProjects/crawler/lib/jobs/generate_xml.rb:21:in `perform'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/activerecord-3.2.3/lib/active_record/relation/batches.rb:72:in `find_in_batches'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/activerecord-3.2.3/lib/active_record/querying.rb:8:in `__send__'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/activerecord-3.2.3/lib/active_record/querying.rb:8:in `find_in_batches'
/home/netserv/RubymineProjects/crawler/lib/jobs/generate_xml.rb:20:in `perform'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:155:in `call'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:155:in `_nested_structures'
/home/netserv/.rvm/gems/ruby-1.8.7-p357/gems/builder-3.0.0/lib/builder/xmlbase.rb:63:in `method_missing'
/home/netserv/RubymineProjects/crawler/lib/jobs/generate_xml.rb:19:in `perform'

Answer 1

find_in_batches returns arrays. Inside the Postings block, you could do this:

  Result.find_in_batches do |results|
    results.each do
      xml.Posting do
        xml.JobID result.job_id
        xml.JobURL result.job_url
      end
    end
  end

But why even bother with find_in_batches?