From 2975e1fc42709cfd8c2331a57dd91091f6ad2ef4 Mon Sep 17 00:00:00 2001
From: Markus Padourek <markus.padourek@gmail.com>
Date: Mon, 12 Sep 2016 15:51:51 +0100
Subject: [PATCH] Allow initialising ObjectType with private state.

---
 graphene/types/objecttype.py            |  2 +-
 graphene/types/tests/test_objecttype.py | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/graphene/types/objecttype.py b/graphene/types/objecttype.py
index 273049ba..91b74c0f 100644
--- a/graphene/types/objecttype.py
+++ b/graphene/types/objecttype.py
@@ -95,7 +95,7 @@ class ObjectType(six.with_metaclass(ObjectTypeMeta)):
         if kwargs:
             for prop in list(kwargs):
                 try:
-                    if isinstance(getattr(self.__class__, prop), property):
+                    if isinstance(getattr(self.__class__, prop), property) or prop.startswith('_'):
                         setattr(self, prop, kwargs.pop(prop))
                 except AttributeError:
                     pass
diff --git a/graphene/types/tests/test_objecttype.py b/graphene/types/tests/test_objecttype.py
index a6196b1f..eb297917 100644
--- a/graphene/types/tests/test_objecttype.py
+++ b/graphene/types/tests/test_objecttype.py
@@ -64,6 +64,20 @@ def test_generate_objecttype_with_fields():
     assert 'field' in MyObjectType._meta.fields
 
 
+def test_generate_objecttype_with_private_attributes():
+    class MyObjectType(ObjectType):
+        _private_state = None
+
+    assert '_private_state' not in MyObjectType._meta.fields
+    assert hasattr(MyObjectType, '_private_state')
+
+    m = MyObjectType(_private_state='custom')
+    assert m._private_state == 'custom'
+
+    with pytest.raises(TypeError):
+        MyObjectType(_other_private_state='Wrong')
+
+
 def test_ordered_fields_in_objecttype():
     class MyObjectType(ObjectType):
         b = Field(MyType)