Add round_price

We add a common method to round prices that are stored using the price digits.
It is useless to use the digits from the field because it can not be changed in
any other way than by configuration.

issue9146
review299521002

purchase.py

@@ -1,7 +1,5 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-from decimal import Decimal
-
 from trytond import backend
 from trytond.i18n import gettext
 from trytond.model import ModelSQL, ValueMixin, fields
@@ -11,6 +9,7 @@ from trytond.pool import Pool, PoolMeta
 from trytond.transaction import Transaction
 from trytond.tools.multivalue import migrate_property
 
+from trytond.modules.product import round_price
 from trytond.modules.purchase.purchase import (
     get_shipments_returns, search_shipments_returns)
 
@@ -181,11 +180,9 @@ class Line(metaclass=PoolMeta):
         Currency = pool.get('currency.currency')
         move = super().get_move(move_type)
         if move and self.purchase.customer:
-            digits = move.__class__.cost_price.digits
             cost_price = Currency.compute(
                 move.currency, move.unit_price, move.company.currency)
-            move.cost_price = cost_price.quantize(
-                Decimal(str(10.0 ** -digits[1])))
+            move.cost_price = round_price(cost_price)
         return move
 
 

stock.py

@@ -17,6 +17,7 @@ from trytond.transaction import Transaction
 from trytond.tools import grouped_slice, cursor_dict
 
 from trytond.modules.sale.stock import process_sale
+from trytond.modules.product import round_price
 from trytond.modules.purchase.stock import process_purchase
 
 
@@ -402,7 +403,6 @@ class ShipmentDrop(Workflow, ModelSQL, ModelView):
         Move = pool.get('stock.move')
 
         to_save = []
-        cost_exp = Decimal(str(10.0 ** -Move.cost_price.digits[1]))
         for shipment in shipments:
             product_qty = defaultdict(int)
             product_cost = defaultdict(int)
@@ -454,7 +454,7 @@ class ShipmentDrop(Workflow, ModelSQL, ModelView):
             for product, cost in product_cost.items():
                 qty = Decimal(str(s_product_qty[product]))
                 if qty:
-                    product_cost[product] = (cost / qty).quantize(cost_exp)
+                    product_cost[product] = round_price(cost / qty)
             for c_move in list(shipment.customer_moves) + to_save:
                 if c_move.id is not None and c_move.state == 'cancel':
                     continue

tryton.cfg

@@ -3,6 +3,7 @@ version=5.5.0
 depends:
     company
     ir
+    product
     purchase
     purchase_request
     sale