Improved Promise connection abstraction

Author: syrusakbary

graphene/relay/connection.py

@@ -118,29 +118,34 @@ def type(self):
         ).format(str(self), connection_type)
         return connection_type
 
+    @classmethod
+    def resolve_connection(cls, connection_type, args, resolved):
+        if isinstance(resolved, connection_type):
+            return resolved
+
+        assert isinstance(resolved, Iterable), (
+            'Resolved value from the connection field have to be iterable or instance of {}. '
+            'Received "{}"'
+        ).format(connection_type, resolved)
+        connection = connection_from_list(
+            resolved,
+            args,
+            connection_type=connection_type,
+            edge_type=connection_type.Edge,
+            pageinfo_type=PageInfo
+        )
+        connection.iterable = resolved
+        return connection
+
     @classmethod
     def connection_resolver(cls, resolver, connection_type, root, args, context, info):
-        p = Promise.resolve(resolver(root, args, context, info))
-
-        def resolve_connection(resolved):
-            if isinstance(resolved, connection_type):
-                return resolved
-
-            assert isinstance(resolved, Iterable), (
-                'Resolved value from the connection field have to be iterable or instance of {}. '
-                'Received "{}"'
-            ).format(connection_type, resolved)
-            connection = connection_from_list(
-                resolved,
-                args,
-                connection_type=connection_type,
-                edge_type=connection_type.Edge,
-                pageinfo_type=PageInfo
-            )
-            connection.iterable = resolved
-            return connection
-
-        return p.then(resolve_connection)
+        resolved = resolver(root, args, context, info)
+
+        on_resolve = partial(cls.resolve_connection, connection_type, args)
+        if isinstance(resolved, Promise):
+            return resolved.then(on_resolve)
+
+        return on_resolve(resolved)
 
     def get_resolver(self, parent_resolver):
         resolver = super(IterableConnectionField, self).get_resolver(parent_resolver)