Use Constraint instance in ModelSQL._sql_constraints

issue4814
review15491002

asset.py

@@ -8,7 +8,7 @@ from dateutil import rrule
 from itertools import groupby
 from cached_property import cached_property
 
-from trytond.model import Workflow, ModelSQL, ModelView, fields
+from trytond.model import Workflow, ModelSQL, ModelView, fields, Unique
 from trytond.pyson import Eval, Bool, If
 from trytond.pool import Pool
 from trytond.transaction import Transaction
@@ -170,8 +170,9 @@ class Asset(Workflow, ModelSQL, ModelView):
     @classmethod
     def __setup__(cls):
         super(Asset, cls).__setup__()
+        table = cls.__table__()
         cls._sql_constraints = [
-            ('invoice_line_uniq', 'UNIQUE(supplier_invoice_line)',
+            ('invoice_line_uniq', Unique(table, table.supplier_invoice_line),
                 'Supplier Invoice Line can be used only once on asset.'),
             ]
         cls._error_messages.update({

invoice.py

@@ -1,6 +1,6 @@
 # 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 trytond.model import fields
+from trytond.model import fields, Unique
 from trytond.pyson import Eval
 from trytond.pool import Pool, PoolMeta
 
@@ -27,8 +27,9 @@ class InvoiceLine:
     @classmethod
     def __setup__(cls):
         super(InvoiceLine, cls).__setup__()
+        table = cls.__table__()
         cls._sql_constraints += [
-            ('asset_uniq', 'UNIQUE(asset)',
+            ('asset_uniq', Unique(table, table.asset),
                 'Asset can be used only once on invoice line!'),
             ]