PoS Product packaging multi barcode

This module extends the Point of Sale so that product packagings with several barcodes can be used at the till. It relies on the product packaging multi barcode feature, which lets one packaging carry a list of barcodes, and makes that list available inside the Point of Sale.

What changes for users:

• In the Point of Sale, scanning any barcode belonging to a packaging will select that packaging, not only the packaging's main barcode.
• The list of barcodes of each packaging is prepared automatically and loaded into the Point of Sale session, so cashiers do not need to do anything special.

Where it appears: this works in the Point of Sale interface when scanning products or packagings. There are no new menus or buttons; the change is in how barcodes are recognised during a sale.

Which records it touches: it extends product.packaging by adding a computed field that stores the packaging's barcodes as a text list, and it extends pos.session so that this field is included when the Point of Sale loads packaging data. The Point of Sale's local database is also extended so that every barcode of a packaging points to the right packaging.

Business rules: the module is installed automatically when both the Point of Sale and the multi barcode packaging features are present. It does not add checks, emails or scheduled jobs; it only makes existing multiple barcodes usable at the till.