allow route-id to be optional

party.py

@@ -6,20 +6,48 @@
 from trytond.pool import PoolMeta
 from trytond.exceptions import UserError
 from trytond.i18n import gettext
+from trytond.model import fields
 
 
 class Party(metaclass=PoolMeta):
     __name__ = 'party.party'
 
+    xrechnung_routeid = fields.Boolean(
+        string='X-Rechnung Route-ID',
+        help='Enables the need for an XRechnung route ID at the party ' +
+        'for exporting the XRechnung.')
+
     def get_xrechnung_route_id(self):
         """ search for route-id at party, fire-exception if missing
         """
         for ident in self.identifiers:
             if ident.type == 'edoc_route_id':
                 return ident.code
-        raise UserError(gettext(
-            'edocument_xrechnung.msg_missing_xrechnung_route_id',
-            partyname=self.rec_name))
+
+        if self.xrechnung_routeid:
+            raise UserError(gettext(
+                'edocument_xrechnung.msg_missing_xrechnung_route_id',
+                partyname=self.rec_name))
+
+    @classmethod
+    def default_xrechnung_routeid(cls):
+        """ default for needs-route-id
+
+        Returns:
+            bool: default False
+        """
+        return False
+
+    @classmethod
+    def validate(cls, records):
+        """ validate setup of xrechnung route id
+
+        Args:
+            records (list): records of party.party
+        """
+        super(Party, cls).validate(records)
+        for record in records:
+            record.get_xrechnung_route_id()
 
 # end Party