Add load_many to DataLoader (#1528)

RELEASE.md

@@ -0,0 +1,3 @@
+Release type: patch
+
+This release adds `load_many` to `DataLoader`.

docs/guides/dataloaders.md

@@ -74,6 +74,13 @@ await loader.load(1)
 
 Will result in only one call to `load_users`.
 
+And finally sometimes we'll want to load more than one key at a time. In those
+cases we can use the `load_many` method.
+
+```python
+[user_a, user_b, user_c] = await loader.load_many([1, 2, 3])
+```
+
 ## Usage with GraphQL
 
 Let's see an example of how you can use DataLoaders with GraphQL:

strawberry/dataloader.py

@@ -1,9 +1,19 @@
 import dataclasses
-from asyncio import create_task, get_event_loop
+from asyncio import create_task, gather, get_event_loop
 from asyncio.events import AbstractEventLoop
 from asyncio.futures import Future
 from dataclasses import dataclass
-from typing import Any, Awaitable, Callable, Dict, Generic, List, Optional, TypeVar
+from typing import (
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    Generic,
+    Iterable,
+    List,
+    Optional,
+    TypeVar,
+)
 
 from .exceptions import WrongNumberOfResultsReturned
 
@@ -78,6 +88,9 @@ def load(self, key: K) -> Awaitable[T]:
 
         return future
 
+    def load_many(self, keys: Iterable[K]) -> Awaitable[List[T]]:
+        return gather(*map(self.load, keys))
+
 
 def should_create_new_batch(loader: DataLoader, batch: Batch) -> bool:
     if (

tests/test_dataloaders.py

@@ -23,6 +23,10 @@ async def idx(keys):
     assert value_b == 2
     assert value_c == 3
 
+    values = await loader.load_many([1, 2, 3, 4, 5, 6])
+
+    assert values == [1, 2, 3, 4, 5, 6]
+
 
 async def test_gathering(mocker):
     async def idx(keys):