# File app/controllers/attendance_adm_controller.rb, line 103
  def certificates_by_attendances
    min = params[:min_attend].to_i
    if min <= 0
      redirect_to :action => 'list', :conference_id => @conference
      return false
    end

    totals = Attendance.totalized_for_conference(@conference)
    people = totals.keys.map {|num| next if num < min; totals[num]}.
      select {|p| p}.flatten

    send_data(certificate_pdf_for(people, CertifFormat.find(1)),
              :filename => 'certificate.pdf', 
              :type => 'application/pdf')
  end