Help refactoring this nasty Ruby if/else statement

Question

So I have this big, hairy if/else statement. I pass a tracking number to it, and then it determines what type of tracking number it is.

How can I simplify this thing? Sp

Answer 1

Try this. I rewrote it using case and regular expressions. I also used :symbols instead of "strings" for the return values, but you can change that back.

tracking_service = case number
  when /^.Z/ then :ups
  when /^Q/ then :dhl
  when /^96.{20}$/ then :fedex
  when /^[HK].{10}$/ then :ups
else
  check_response(number) if num_length == 18 || num_length == 20
  case num_length
    when 17 then :dhlgm
    when 13, 20, 22, 30 then :usps
    when 12, 15, 19 then :fedex
    when 10, 11 then :dhl
    else false
  end
end