Store directly sequence type to sequence

configuration.py

@@ -1,7 +1,7 @@
 # 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, ModelSQL
-from trytond.pyson import Eval
+from trytond.pyson import Eval, Id
 from trytond.pool import PoolMeta, Pool
 from trytond.modules.company.model import (
     CompanyMultiValueMixin, CompanyValueMixin)
@@ -17,7 +17,8 @@ class Configuration(CompanyMultiValueMixin, metaclass=PoolMeta):
             'Product Cost Plan Sequence', domain=[
                 ('company', 'in',
                     [Eval('context', {}).get('company', -1), None]),
-                ('code', '=', 'product_cost_plan'),
+                ('sequence_type', '=', Id('product_cost_plan',
+                        'sequence_type_product_cost_plan')),
                 ], required=True))
 
     @classmethod
@@ -36,5 +37,6 @@ class ConfigurationProductcostPlan(ModelSQL, CompanyValueMixin):
             'Product Cost Plan Sequence', domain=[
                 ('company', 'in',
                     [Eval('context', {}).get('company', -1), None]),
-                ('code', '=', 'product_cost_plan'),
+                ('sequence_type', '=', Id('product_cost_plan',
+                        'sequence_type_product_cost_plan')),
                 ], required=True)

plan.py

@@ -446,15 +446,12 @@ class Plan(ModelSQL, ModelView):
 
     @classmethod
     def create(cls, vlist):
-        Sequence = Pool().get('ir.sequence')
         Config = Pool().get('production.configuration')
 
         vlist = [x.copy() for x in vlist]
         config = Config(1)
         for values in vlist:
-            values['number'] = Sequence.get_id(
-                config.product_cost_plan_sequence and
-                config.product_cost_plan_sequence.id)
+            values['number'] = config.product_cost_plan_sequence.get()
         return super(Plan, cls).create(vlist)
 
     @classmethod

plan.xml

@@ -19,7 +19,6 @@
         </record>
         <record model="ir.sequence.type" id="sequence_type_product_cost_plan">
             <field name="name">Product Cost Plan</field>
-            <field name="code">product_cost_plan</field>
         </record>
         <record model="ir.sequence.type-res.group"
             id="sequence_type_product_cost_plan_group_admin">
@@ -34,7 +33,7 @@
 
         <record model="ir.sequence" id="sequence_product_cost_plan">
             <field name="name">Product Cost Plan</field>
-            <field name="code">product_cost_plan</field>
+            <field name="sequence_type" ref="sequence_type_product_cost_plan"/>
         </record>
 
         <!-- product.cost.plan -->