Module: Purchase

• state
• order_line
• invoice_ids

precision = self.env['decimal.precision'].precision_get('Product Unit')
for order in self:
            if order.state != 'purchase':
                order.invoice_status = 'no'
                continue

            if any(
                not float_is_zero(line.qty_to_invoice, precision_digits=precision)
                for line in order.order_line.filtered(lambda l: not l.display_type)
            ):
                order.invoice_status = 'to invoice'
            elif (
                all(
                    float_is_zero(line.qty_to_invoice, precision_digits=precision)
                    for line in order.order_line.filtered(lambda l: not l.display_type)
                )
                and order.invoice_ids
            ):
                order.invoice_status = 'invoiced'
            else:
                order.invoice_status = 'no'

• invoice_status