Made Relationshiploader utilize the new and improved DataLoader imple…

…mentation housed inside graphene, if possible (graphene >=3.1.1)

graphene_sqlalchemy/batching.py

@@ -2,15 +2,28 @@
 from asyncio import get_event_loop
 from typing import Any, Dict
 
-import aiodataloader
 import sqlalchemy
 from sqlalchemy.orm import Session, strategies
 from sqlalchemy.orm.query import QueryContext
 
 from .utils import is_graphene_version_less_than, is_sqlalchemy_version_less_than
 
 
-class RelationshipLoader(aiodataloader.DataLoader):
+def get_data_loader_impl() -> Any:  # pragma: no cover
+    """Graphene >= 3.1.1 ships a copy of aiodataloader with minor fixes. To preserve backward-compatibility,
+    aiodataloader is used in conjunction with older versions of graphene"""
+    if is_graphene_version_less_than("3.1.1"):
+        from aiodataloader import DataLoader
+    else:
+        from graphene.utils.dataloader import DataLoader
+
+    return DataLoader
+
+
+DataLoader = get_data_loader_impl()
+
+
+class RelationshipLoader(DataLoader):
     cache = False
 
     def __init__(self, relationship_prop, selectin_loader):
@@ -92,20 +105,6 @@ async def batch_load_fn(self, parents):
 ] = {}
 
 
-def get_data_loader_impl() -> Any:  # pragma: no cover
-    """Graphene >= 3.1.1 ships a copy of aiodataloader with minor fixes. To preserve backward-compatibility,
-    aiodataloader is used in conjunction with older versions of graphene"""
-    if is_graphene_version_less_than("3.1.1"):
-        from aiodataloader import DataLoader
-    else:
-        from graphene.utils.dataloader import DataLoader
-
-    return DataLoader
-
-
-DataLoader = get_data_loader_impl()
-
-
 def get_batch_resolver(relationship_prop):
     """Get the resolve function for the given relationship."""