wb = xlsx_package.workbook
wb.add_worksheet(:name => "registrations") do |sheet|
  bold_style = wb.styles.add_style(:b => true)
  row = ["Attended", "Name", "Nickname", "Affilation", "Email", "Social events",
    "With partner", "Needs access", "Other needs", "Arrival", "Departure"]
  sheet.add_row row, :style => bold_style

  @registrations.each do |reg|
    row = []
    row << reg.attended
    row << reg.name
    row << reg.nickname
    row << reg.affiliation
    row << reg.email
    row << reg.attending_social_events
    row << reg.attending_with_partner
    row << reg.handicapped_access_required
    row << reg.other_needs
    row << reg.arrival
    row << reg.departure
    sheet.add_row row
  end
  sheet.column_info[8].width = [sheet.column_info[8].width, 30].min
end