fix: Support bytes serialization in CustomEncoder for Interactions API.

google/genai/_interactions/_utils/_json.py

@@ -13,12 +13,13 @@
 # limitations under the License.
 #
 
+import base64
+from datetime import datetime
 import json
 from typing import Any
-from datetime import datetime
-from typing_extensions import override
 
 import pydantic
+from typing_extensions import override
 
 from .._compat import model_dump
 
@@ -47,4 +48,6 @@ def default(self, o: Any) -> Any:
             return o.isoformat()
         if isinstance(o, pydantic.BaseModel):
             return model_dump(o, exclude_unset=True, mode="json", by_alias=True)
+        if isinstance(o, bytes):
+            return base64.b64encode(o).decode("ascii")
         return super().default(o)

google/genai/tests/interactions/test_utils.py

@@ -0,0 +1,39 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import base64
+import json
+from ..._interactions._utils._json import openapi_dumps
+
+
+def test_openapi_dumps_bytes():
+  data = {"image": b"123", "text": "hello"}
+  expected_image_b64 = base64.b64encode(b"123").decode("ascii")
+
+  result_bytes = openapi_dumps(data)
+  result_dict = json.loads(result_bytes.decode("utf-8"))
+
+  assert result_dict["image"] == expected_image_b64
+  assert result_dict["text"] == "hello"
+
+
+def test_openapi_dumps_nested_bytes():
+  data = {"outer": {"inner": b"binary_data"}}
+  expected_b64 = base64.b64encode(b"binary_data").decode("ascii")
+
+  result_bytes = openapi_dumps(data)
+  result_dict = json.loads(result_bytes.decode("utf-8"))
+
+  assert result_dict["outer"]["inner"] == expected_b64