exception when creating a barcode without an id

[nomaster]

when I create a barcode object (on the CLI) without specifying an id, Rails throws an exception. Investigation shows a spurious requirement of the id property in the model file.

[YtvwlD]

I'm no expert in how Rails handles IDs.
But from the view of constructing a database, adding artificial IDs to tables if real-world IDs exist is superfluous.
But giving artifical (numeric) IDs to barcodes would be consistent with drinks and users.
This is difficicult.