(relay connection) promisify result from async method

graphene/relay/connection.py

@@ -12,6 +12,7 @@ from ..types import (AbstractType, Boolean, Enum, Int, Interface, List, NonNull,
 from ..types.field import Field
 from ..types.objecttype import ObjectType, ObjectTypeMeta
 from ..types.options import Options
+from ..utils.compat_asyncio_promise import promisify
 from ..utils.is_base_type import is_base_type
 from ..utils.props import props
 from .node import is_node
@@ -139,7 +140,7 @@ class IterableConnectionField(Field):
 
     @classmethod
     def connection_resolver(cls, resolver, connection_type, root, args, context, info):
-        resolved = resolver(root, args, context, info)
+        resolved = promisify(resolver(root, args, context, info))
 
         on_resolve = partial(cls.resolve_connection, connection_type, args)
         if isinstance(resolved, Promise):

graphene/utils/compat_asyncio_promise.py

@@ -0,0 +1,12 @@
+import promise
+
+def promisify(resolved):
+    try:
+        import asyncio
+        if isinstance(resolved, asyncio.Future) or \
+            asyncio.iscoroutine(resolved):
+            return promise.promisify(resolved)
+    except:
+        pass
+
+    return resolved