Streaming CSV file to the Client with Rails 3.1

controller_not_dry.rb

format.csv do
  @scheduled_session = Session.find(params[:id])
  @applicants = @scheduled_session.applicant_signups
  filename = "#{@scheduled_session.title.parameterize.downcase}_applicant_list_#{Time.now.strftime('%d%m%Y')}.csv"
  headers['Content-Disposition'] = 'attachment; filename="' + filename + '"'
  titles = [
    "Title", "First Name", "Last Name", "DOB Day", "DOB Month", "DOB Year", "Nationality", \
    "Email", "Mobile Number", "Address Line 1", "Address Line 2", "Place of Work", \
    "Discipline/Speciality", "Job Title", "Key Responsibilities", "Payment Ref."
  ]
  attribs = [
    lambda {|r, event| r.title},
    lambda {|r, event| r.first_name},
    lambda {|r, event| r.last_name},
    lambda {|r, event| r.dob_day},
    lambda {|r, event| r.dob_month},
    lambda {|r, event| r.dob_year},
    lambda {|r, event| r.nationality},        
    lambda {|r, event| r.email},
    lambda {|r, event| r.phone_number},
    lambda {|r, event| r.address_line1},
    lambda {|r, event| r.address_line2},
    lambda {|r, event| r.work_place},
    lambda {|r, event| r.speciality},
    lambda {|r, event| r.occupation}, # job title
    lambda {|r, event| r.responsibilities},
    lambda {|r, event| "#{event.code}R000#{r.id}"}
    ]
  self.response_body = CSVStreamer.new(@applicants, @scheduled_session, titles, attribs)
end

csv_streamer.rb

class CSVStreamer
  attr_reader :records, :event, :titles, :attribs

  def initialize(records, event, titles, attribs)
    @event = event
    @records = records
    @titles = titles
    @attribs = attribs
  end
  
  def each
    yield CSV.generate_line(titles)
    records.each do |r|
      yield csv_row(r)
    end    
  end
  
  def csv_row(r)
    CSV.generate_line(attribs.map{|a| a.call(r,event)})
  end
end

note.md

Here's some code from a session of hacking no where close to being DRY.