Purchase Order Line Invoicing

This module adds a way to group purchase order lines from the same supplier into one vendor bill.

• On a supplier's contact form, a new "Purchase Lines" button shows how many purchase order lines exist for that supplier (including child contacts) and opens the list of those lines.
• From the list of purchase order lines, users can run the "Create Invoice" action. A wizard opens showing each selected line with its order, product, description, unit price, ordered quantity, received quantity, already invoiced quantity and subtotal.
• The wizard pre-fills the "Quantity to Invoice" on each line with the quantity received minus the quantity already invoiced (never below zero), and users can adjust it.
• A check prevents mixing lines from different suppliers: all selected lines must belong to one supplier, otherwise an error is shown. If no line is selected, an error is also shown.
• Clicking "Create Invoice" creates a vendor bill (in_invoice) for that supplier, using the supplier's fiscal position and a purchase journal matching the company and currency, and sets the bill's origin to the names of the involved purchase orders. The bill lines are built from the purchase order lines, and the user is taken to the created bill.

The module touches res.partner, purchase.order.line and account.move, and is available to purchase users.