Fix property migration

__init__.py

@@ -1,11 +1,11 @@
 # The COPYRIGHT file at the top level of this repository contains the full
 # copyright notices and license terms.
 from trytond.pool import Pool
-from .party import Party, PartyParty
+from .party import Party, PartyInvoiceTo
 
 
 def register():
     Pool.register(
         Party,
-        PartyParty,
+        PartyInvoiceTo,
         module='account_invoice_party_invoice_to', type_='model')

party.py

@@ -2,11 +2,13 @@
 # this repository contains the full copyright notices and license terms.
 from trytond.model import ModelSQL, fields
 from trytond.pool import PoolMeta, Pool
-from trytond.modules.company.model import CompanyValueMixin
 from trytond import backend
 from trytond.tools.multivalue import migrate_property
+from trytond.modules.company.model import CompanyValueMixin
+
+
+__all__ = ['Party', 'PartyInvoiceTo']
 
-__all__ = ['Party', 'PartyParty']
 parties_names = ['customer_to_invoice', 'supplier_to_invoice']
 
 
@@ -18,18 +20,23 @@ class Party:
             fields.Many2One('party.party', 'Customer to invoice'))
     supplier_to_invoice = fields.MultiValue(
             fields.Many2One('party.party', 'Supplier to invoice'))
+    invoice_to_parties = fields.One2Many('party.party.invoice_to',
+        'party', 'Invoice to parties')
 
     @classmethod
     def multivalue_model(cls, field):
         pool = Pool()
         if field in parties_names:
-            return pool.get('party.party.party')
+            return pool.get('party.party.invoice_to')
         return super(Party, cls).multivalue_model(field)
 
 
-class PartyParty(ModelSQL, CompanyValueMixin):
-    "Party Party"
-    __name__ = 'party.party.party'
+class PartyInvoiceTo(ModelSQL, CompanyValueMixin):
+    "Party Invoice to"
+    __name__ = 'party.party.invoice_to'
+
+    party = fields.Many2One('party.party', 'Party', ondelete='CASCADE',
+        select=True)
     customer_to_invoice = fields.Many2One('party.party', 'Customer to invoice')
     supplier_to_invoice = fields.Many2One('party.party', 'Supplier to invoice')
 
@@ -38,7 +45,7 @@ class PartyParty(ModelSQL, CompanyValueMixin):
         TableHandler = backend.get('TableHandler')
         exist = TableHandler.table_exist(cls._table)
 
-        super(PartyParty, cls).__register__(module_name)
+        super(PartyInvoiceTo, cls).__register__(module_name)
 
         if not exist:
             cls._migrate_property([], [], [])
@@ -49,4 +56,4 @@ class PartyParty(ModelSQL, CompanyValueMixin):
         value_names.extend(parties_names)
         fields.append('company')
         migrate_property('party.party',
-            field_names, cls, value_names, fields=fields)
+            field_names, cls, value_names, parent='party', fields=fields)