Make sure MemberInfo.customers is sorted by person number

also improve the str() method a bit

corepos/db/office_op/model.py

@@ -1017,6 +1017,7 @@ class MemberInfo(Base):
     customers = orm.relationship(
         CustData,
         primaryjoin=CustData.card_number == card_number,
+        order_by=CustData.person_number,
         foreign_keys=[CustData.card_number],
         back_populates='member_info',
         remote_side=CustData.card_number,
@@ -1073,7 +1074,10 @@ class MemberInfo(Base):
         return '{} {}'.format(self.first_name or '', self.last_name or '').strip()
 
     def __str__(self):
-        return self.full_name
+        name = self.full_name
+        if name:
+            return name
+        return "Member Info #{}".format(self.card_number)
 
     def split_street(self):
         """