Full mypy --strict type checking pass

fastapi_cache/backends/dynamodb.py

@@ -1,11 +1,16 @@
 import datetime
-from typing import Optional, Tuple
+from typing import TYPE_CHECKING, Optional, Tuple
 
 from aiobotocore.client import AioBaseClient
-from aiobotocore.session import get_session, AioSession
+from aiobotocore.session import AioSession, get_session
 
 from fastapi_cache.backends import Backend
 
+if TYPE_CHECKING:
+    from types_aiobotocore_dynamodb import DynamoDBClient
+else:
+    DynamoDBClient = AioBaseClient
+
 
 class DynamoBackend(Backend):
     """
@@ -25,9 +30,13 @@ class DynamoBackend(Backend):
         >> FastAPICache.init(dynamodb)
     """
 
+    client: DynamoDBClient
+    session: AioSession
+    table_name: str
+    region: Optional[str]
+
     def __init__(self, table_name: str, region: Optional[str] = None) -> None:
         self.session: AioSession = get_session()
-        self.client: Optional[AioBaseClient] = None  # Needs async init
         self.table_name = table_name
         self.region = region
 
@@ -60,6 +69,7 @@ class DynamoBackend(Backend):
         response = await self.client.get_item(TableName=self.table_name, Key={"key": {"S": key}})
         if "Item" in response:
             return response["Item"].get("value", {}).get("B")
+        return None
 
     async def set(self, key: str, value: bytes, expire: Optional[int] = None) -> None:
         ttl = (