From 949922ef2cb7a7c6e4a83cb91856c70728acd806 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Sat, 25 Jun 2022 11:19:11 -0500
Subject: [PATCH] Fix exception when as_dict is called on a TemplateState
 (#73984)

---
 homeassistant/helpers/template.py |  4 +++-
 tests/helpers/test_template.py    | 10 ++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/homeassistant/helpers/template.py b/homeassistant/helpers/template.py
index eca76a8c7bc..53e2eb122f6 100644
--- a/homeassistant/helpers/template.py
+++ b/homeassistant/helpers/template.py
@@ -5,7 +5,7 @@ from ast import literal_eval
 import asyncio
 import base64
 import collections.abc
-from collections.abc import Callable, Generator, Iterable
+from collections.abc import Callable, Collection, Generator, Iterable
 from contextlib import contextmanager, suppress
 from contextvars import ContextVar
 from datetime import datetime, timedelta
@@ -54,6 +54,7 @@ from homeassistant.util import (
     slugify as slugify_util,
 )
 from homeassistant.util.async_ import run_callback_threadsafe
+from homeassistant.util.read_only_dict import ReadOnlyDict
 from homeassistant.util.thread import ThreadWithException
 
 from . import area_registry, device_registry, entity_registry, location as loc_helper
@@ -764,6 +765,7 @@ class TemplateStateBase(State):
         self._hass = hass
         self._collect = collect
         self._entity_id = entity_id
+        self._as_dict: ReadOnlyDict[str, Collection[Any]] | None = None
 
     def _collect_state(self) -> None:
         if self._collect and _RENDER_INFO in self._hass.data:
diff --git a/tests/helpers/test_template.py b/tests/helpers/test_template.py
index 69a3af22759..59b653bc23e 100644
--- a/tests/helpers/test_template.py
+++ b/tests/helpers/test_template.py
@@ -26,6 +26,7 @@ from homeassistant.core import HomeAssistant
 from homeassistant.exceptions import TemplateError
 from homeassistant.helpers import device_registry as dr, entity, template
 from homeassistant.helpers.entity_platform import EntityPlatform
+from homeassistant.helpers.json import json_dumps
 from homeassistant.setup import async_setup_component
 import homeassistant.util.dt as dt_util
 from homeassistant.util.unit_system import UnitSystem
@@ -3841,3 +3842,12 @@ async def test_template_states_blocks_setitem(hass):
     template_state = template.TemplateState(hass, state, True)
     with pytest.raises(RuntimeError):
         template_state["any"] = "any"
+
+
+async def test_template_states_can_serialize(hass):
+    """Test TemplateState is serializable."""
+    hass.states.async_set("light.new", STATE_ON)
+    state = hass.states.get("light.new")
+    template_state = template.TemplateState(hass, state, True)
+    assert template_state.as_dict() is template_state.as_dict()
+    assert json_dumps(template_state) == json_dumps(template_state)