Use Graphene DataLoader in graphene>=3.1.1 (#360)

* Use Graphene Datolader in graphene>=3.1.1

Author: erikwrede

graphene_sqlalchemy/batching.py

@@ -1,13 +1,30 @@
+"""The dataloader uses "select in loading" strategy to load related entities."""
+from typing import Any
+
 import aiodataloader
 import sqlalchemy
 from sqlalchemy.orm import Session, strategies
 from sqlalchemy.orm.query import QueryContext
 
-from .utils import is_sqlalchemy_version_less_than
+from .utils import (is_graphene_version_less_than,
+                    is_sqlalchemy_version_less_than)
 
 
-def get_batch_resolver(relationship_prop):
+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):
     # Cache this across `batch_load_fn` calls
     # This is so SQL string generation is cached under-the-hood via `bakery`
     selectin_loader = strategies.SelectInLoader(relationship_prop, (('lazy', 'selectin'),))

graphene_sqlalchemy/utils.py

@@ -151,11 +151,16 @@ def sort_argument_for_model(cls, has_default=True):
     return Argument(List(enum), default_value=enum.default)
 
 
-def is_sqlalchemy_version_less_than(version_string):
+def is_sqlalchemy_version_less_than(version_string):  # pragma: no cover
     """Check the installed SQLAlchemy version"""
     return pkg_resources.get_distribution('SQLAlchemy').parsed_version < pkg_resources.parse_version(version_string)
 
 
+def is_graphene_version_less_than(version_string):  # pragma: no cover
+    """Check the installed graphene version"""
+    return pkg_resources.get_distribution('graphene').parsed_version < pkg_resources.parse_version(version_string)
+
+
 class singledispatchbymatchfunction:
     """
     Inspired by @singledispatch, this is a variant that works using a matcher function
@@ -197,6 +202,7 @@ def safe_isinstance_checker(arg):
             return isinstance(arg, cls)
         except TypeError:
             pass
+
     return safe_isinstance_checker
 
 
@@ -210,5 +216,6 @@ def registry_sqlalchemy_model_from_str(model_name: str) -> Optional[Any]:
 
 class DummyImport:
     """The dummy module returns 'object' for a query for any member"""
+
     def __getattr__(self, name):
         return object