Example hacky code from the Jeremy Corbyn Labour leadership campaign 2015

convert.rb

require 'csv'
require 'date'
require 'chronic'

HEADERS_TO_KEEP = ['MembershipNumber', 'Title', 'LastName', 'PreferredFirstName', 'DateOfBirth', 'AddressLine1', 'AddressLine2', 'AddressLine3', 'Town', 'Country Code', 'County', 'PostCode', 'Email', 'MobilePhoneNumber', 'PhoneNumber', 'RegionName', 'ConstituencyName', 'TradeUnion', 'PrimaryStatus'] #, 'JoinedDate'

Dir.entries('to_convert')[2..999].each do |file|
  members = CSV.read("to_convert/#{file}", headers: true, :encoding => 'windows-1251:utf-8')

  # remove unused columns
  members.headers.each do |header|
    unless HEADERS_TO_KEEP.include?(header)
      members.delete(header)
    end
  end

  @registered = CSV.open("converted/registered.csv", 'w')
  @member = CSV.open("converted/members.csv", 'w')

  x = 1
  members.each_slice(4000) do |slice|
    CSV.open("converted/#{file}#{x}", 'w') do |csv|
      slice.each do |row|

        # Remove initials to avoid emails starting 'Dear G'
        if row['PreferredFirstName'] && row['PreferredFirstName'].length == 1
          row['PreferredFirstName'] = nil
        end

        if row['DateOfBirth'] && time = Chronic.parse(row['DateOfBirth'])
          date = time.to_date
          date = date.prev_year(100) if date > Date.today
          row['DateOfBirth'] = date.strftime("%m/%d/%Y")
        end

        if row['PrimaryStatus'] == 'REGISTERED'
          @registered.puts row
        elsif row['PrimaryStatus'] == 'MEMBER'
          @member.puts row
        else
          csv.puts row
        end
      end
    end
    x = x+1
  end
end