From 094f2cbad733e63bff20b70caf398c9b2ade1cbb Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 31 Jul 2023 09:49:02 -0700
Subject: [PATCH] Fix saving subclassed datetime objects in storage (#97502)

---
 homeassistant/helpers/json.py |  2 ++
 tests/common.py               | 11 +++++++++--
 tests/helpers/test_json.py    | 14 ++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/homeassistant/helpers/json.py b/homeassistant/helpers/json.py
index 38c23050885..33054bcb1b0 100644
--- a/homeassistant/helpers/json.py
+++ b/homeassistant/helpers/json.py
@@ -53,6 +53,8 @@ def json_encoder_default(obj: Any) -> Any:
         return obj.as_dict()
     if isinstance(obj, Path):
         return obj.as_posix()
+    if isinstance(obj, datetime.datetime):
+        return obj.isoformat()
     raise TypeError
 
 
diff --git a/tests/common.py b/tests/common.py
index 4fdccced370..542aa0afcee 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -67,7 +67,7 @@ from homeassistant.helpers import (
     storage,
 )
 from homeassistant.helpers.dispatcher import async_dispatcher_connect
-from homeassistant.helpers.json import JSONEncoder
+from homeassistant.helpers.json import JSONEncoder, _orjson_default_encoder
 from homeassistant.helpers.typing import ConfigType, StateType
 from homeassistant.setup import setup_component
 from homeassistant.util.async_ import run_callback_threadsafe
@@ -1260,7 +1260,14 @@ def mock_storage(
         # To ensure that the data can be serialized
         _LOGGER.debug("Writing data to %s: %s", store.key, data_to_write)
         raise_contains_mocks(data_to_write)
-        data[store.key] = json.loads(json.dumps(data_to_write, cls=store._encoder))
+        encoder = store._encoder
+        if encoder and encoder is not JSONEncoder:
+            # If they pass a custom encoder that is not the
+            # default JSONEncoder, we use the slow path of json.dumps
+            dump = ft.partial(json.dumps, cls=store._encoder)
+        else:
+            dump = _orjson_default_encoder
+        data[store.key] = json.loads(dump(data_to_write))
 
     async def mock_remove(store: storage.Store) -> None:
         """Remove data."""
diff --git a/tests/helpers/test_json.py b/tests/helpers/test_json.py
index 419122b018b..7e248c8c381 100644
--- a/tests/helpers/test_json.py
+++ b/tests/helpers/test_json.py
@@ -215,6 +215,20 @@ def test_custom_encoder(tmp_path: Path) -> None:
     assert data == "9"
 
 
+def test_saving_subclassed_datetime(tmp_path: Path) -> None:
+    """Test saving subclassed datetime objects."""
+
+    class SubClassDateTime(datetime.datetime):
+        """Subclass datetime."""
+
+    time = SubClassDateTime.fromtimestamp(0)
+
+    fname = tmp_path / "test6.json"
+    save_json(fname, {"time": time})
+    data = load_json(fname)
+    assert data == {"time": time.isoformat()}
+
+
 def test_default_encoder_is_passed(tmp_path: Path) -> None:
     """Test we use orjson if they pass in the default encoder."""
     fname = tmp_path / "test6.json"