start implement custom identifier

graphene/contrib/sqlalchemy/options.py

@@ -10,6 +10,7 @@ class SQLAlchemyOptions(ObjectTypeOptions):
     def __init__(self, *args, **kwargs):
         super(SQLAlchemyOptions, self).__init__(*args, **kwargs)
         self.model = None
+        self.identifier = None
         self.valid_attrs += VALID_ATTRS
         self.only_fields = None
         self.exclude_fields = []

graphene/contrib/sqlalchemy/types.py

@@ -113,8 +113,9 @@ class SQLAlchemyNode(six.with_metaclass(
     def get_node(cls, id, info=None):
         try:
             model = cls._meta.model
+            identifier = cls._meta.identifier or "id"
             query = get_query(model, info)
-            instance = query.filter(model.id == id).one()
+            instance = query.filter(getattr(model, identifier) == id).one()
             return cls(instance)
         except NoResultFound:
             return None