DynamoDB - Return binary data in right format (#6828)

moto/dynamodb/models/dynamo_type.py

@@ -196,7 +196,7 @@ class DynamoType(object):
 
     def to_json(self) -> Dict[str, Any]:
         # Returns a regular JSON object where the value can still be/contain a DynamoType
-        if self.is_binary():
+        if self.is_binary() and isinstance(self.value, bytes):
             # Binary data cannot be represented in JSON
             # AWS returns a base64-encoded value - the SDK's then convert that back
             return {self.type: base64.b64encode(self.value).decode("utf-8")}

tests/test_dynamodb/test_dynamodb.py

@@ -5745,11 +5745,19 @@ def test_projection_expression_with_binary_attr():
     )
     table = dynamo_resource.Table("test")
     table.put_item(Item={"pk": "pk", "sk": "sk", "key": b"value\xbf"})
-    assert table.get_item(
+
+    item = table.get_item(
         Key={"pk": "pk", "sk": "sk"},
         ExpressionAttributeNames={"#key": "key"},
         ProjectionExpression="#key",
-    )["Item"] == {"key": Binary(b"value\xbf")}
+    )["Item"]
+    assert item == {"key": Binary(b"value\xbf")}
+
+    item = table.scan()["Items"][0]
+    assert item["key"] == Binary(b"value\xbf")
+
+    item = table.query(KeyConditionExpression=Key("pk").eq("pk"))["Items"][0]
+    assert item["key"] == Binary(b"value\xbf")
 
 
 @mock_dynamodb

tests/test_dynamodb/test_dynamodb_batch_get_item.py

@@ -14,7 +14,7 @@ def _create_user_table():
         ProvisionedThroughput={"ReadCapacityUnits": 5, "WriteCapacityUnits": 5},
     )
     client.put_item(
-        TableName="users", Item={"username": {"S": "user1"}, "foo": {"S": "bar"}}
+        TableName="users", Item={"username": {"S": "user1"}, "binaryfoo": {"B": b"bar"}}
     )
     client.put_item(
         TableName="users", Item={"username": {"S": "user2"}, "foo": {"S": "bar"}}
@@ -42,11 +42,9 @@ def test_batch_items_returns_all():
         }
     )["Responses"]["users"]
     assert len(returned_items) == 3
-    assert [item["username"]["S"] for item in returned_items] == [
+    assert {"username": {"S": "user1"}, "binaryfoo": {"B": b"bar"}} in returned_items
-        "user1",
+    assert {"username": {"S": "user2"}, "foo": {"S": "bar"}} in returned_items
-        "user2",
+    assert {"username": {"S": "user3"}, "foo": {"S": "bar"}} in returned_items
-        "user3",
-    ]
 
 
 @mock_dynamodb
@@ -137,12 +135,10 @@ def test_batch_items_with_basic_projection_expression():
         }
     )["Responses"]["users"]
 
-    assert [item["username"]["S"] for item in returned_items] == [
+    assert len(returned_items) == 3
-        "user1",
+    assert {"username": {"S": "user1"}, "binaryfoo": {"B": b"bar"}} in returned_items
-        "user2",
+    assert {"username": {"S": "user2"}, "foo": {"S": "bar"}} in returned_items
-        "user3",
+    assert {"username": {"S": "user3"}, "foo": {"S": "bar"}} in returned_items
-    ]
-    assert [item["foo"]["S"] for item in returned_items] == ["bar", "bar", "bar"]
 
 
 @mock_dynamodb
@@ -165,12 +161,9 @@ def test_batch_items_with_basic_projection_expression_and_attr_expression_names(
     )["Responses"]["users"]
 
     assert len(returned_items) == 3
-    assert [item["username"]["S"] for item in returned_items] == [
+    assert {"username": {"S": "user1"}} in returned_items
-        "user1",
+    assert {"username": {"S": "user2"}} in returned_items
-        "user2",
+    assert {"username": {"S": "user3"}} in returned_items
-        "user3",
-    ]
-    assert [item.get("foo") for item in returned_items] == [None, None, None]
 
 
 @mock_dynamodb