Here in Brazil, we have a standard doc like bank slip with a code bar and 48 digits, like a hash to pay the bills.
In my app, people input these 48 digits. I realized that people are adding twice, three times the bill.
How do u suggest avoiding this, to check this code before saving in order to avoid duplicated code?
Is there a way, to notify the user that the code that he´s input already exists?
Thx in advance