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ruby-on-railsrubystringcredit-cardactivemerchant

String operation in ruby for credit card number

Working on a rails project where there's an order confirmation string with a credit card number with all but the last four digits starred out. What's the proper way to do a string substitution?

What's the operation to get this

credit_card_number = "1111111111111111"

to this?

credit_card_number = "************1111"

Thanks,

Kenji

Solution

  • If you're using ActiveMerchant, ActiveMerchant::Billing::CreditCard has an instance method called display_number which does this e.g. XXXX-XXXX-XXXX-4338

    If you're not, copy activemerchant:

    def last_digits(number)    
  number.to_s.length <= 4 ? number : number.to_s.slice(-4..-1) 
end

def mask(number)
 "XXXX-XXXX-XXXX-#{last_digits(number)}"
end

credit_card_number = "1111111111111111"

display_number = mask credit_card_number