gistfile1.rb

filters[:departure_date].each do |str_date|
  if str_date.size == 8
    updated_date_filters << Date.strptime(str_date, '%d.%m.%y')
  else
    updated_date_filters << str_date
  end
end

#short variant
filters[:departure_date].map!(|d| d.size == 8 ? Date.strptime(d, '%d.%m.%y') : d)