@kahakun I have done a sample app for you to get inspired by
One button for doing the scanning - and one button for actually inputting the value.
I have made it possible to input the barcode manually as barcode scans quickly eats your quota
I hope that will help you to do your app.
Notice that the data is not user-specific - so if you want multiple users to use the app you will need to replace a number of columns. Please test that it actually works correct with user specific variable