Handling international currency input in Ruby on Rails

Question

I have an application that handles currency inputs. However, if you\'re in the US, you might enter a number as 12,345.67; in France, it might be 12.345,67

Answer 1

You need to clean the input so that users can type pretty much whatever they want to, and you'll get something consistent to store in your database. Assuming your model is called "DoughEntry" and your attribute is "amount," and it is stored as an integer.

Here's a method that converts a string input to cents (if the string ends in two digits following a delimeter, it's assumed to be cents). You may wish to make this smarter, but here's the concept:

def convert_to_cents(input)
  if input =~ /^.*[\.,]\d{2}$/ 
    input.gsub(/[^\d-]/,'').to_i
  else
    "#{input.gsub(/[^\d-]/,'')}00".to_i
  end
end

>> convert_to_cents "12,345"
=> 1234500
>> convert_to_cents "12.345,67"
=> 1234567
>> convert_to_cents "$12.345,67"
=> 1234567

Then overwrite the default "amount" accessor, passing it through that method:

class DoughEntry << ActiveRecord::Base

  def amount=(input)
    write_attribute(:amount, convert_to_cents(input))
  end

protected
  def convert_to_cents(input)
    if input =~ /^.*[\.,]\d{2}$/ 
      input.gsub(/[^\d-]/,'').to_i
    else
      "#{input.gsub(/[^\d-]/,'')}00".to_i
    end
  end
end

Now you're storing cents in the database. Radar has the right idea for pulling it back out.