Improve mobile app template handling (#41703)

Co-authored-by: J. Nick Koston <nick@koston.org>

homeassistant/components/mobile_app/webhook.py

@@ -32,10 +32,13 @@ from homeassistant.const import (
     HTTP_CREATED,
 )
 from homeassistant.core import EventOrigin
-from homeassistant.exceptions import HomeAssistantError, ServiceNotFound, TemplateError
-from homeassistant.helpers import config_validation as cv, device_registry as dr
+from homeassistant.exceptions import HomeAssistantError, ServiceNotFound
+from homeassistant.helpers import (
+    config_validation as cv,
+    device_registry as dr,
+    template,
+)
 from homeassistant.helpers.dispatcher import async_dispatcher_send
-from homeassistant.helpers.template import attach
 from homeassistant.helpers.typing import HomeAssistantType
 from homeassistant.util.decorator import Registry
 
@@ -285,7 +288,7 @@ async def webhook_stream_camera(hass, config_entry, data):
 @validate_schema(
     {
         str: {
-            vol.Required(ATTR_TEMPLATE): cv.template,
+            vol.Required(ATTR_TEMPLATE): cv.string,
             vol.Optional(ATTR_TEMPLATE_VARIABLES, default={}): dict,
         }
     }
@@ -295,10 +298,9 @@ async def webhook_render_template(hass, config_entry, data):
     resp = {}
     for key, item in data.items():
         try:
-            tpl = item[ATTR_TEMPLATE]
-            attach(hass, tpl)
+            tpl = template.Template(item[ATTR_TEMPLATE], hass)
             resp[key] = tpl.async_render(item.get(ATTR_TEMPLATE_VARIABLES))
-        except TemplateError as ex:
+        except template.TemplateError as ex:
             resp[key] = {"error": str(ex)}
 
     return webhook_response(resp, registration=config_entry.data)

tests/components/mobile_app/test_webhook.py

@@ -70,13 +70,26 @@ async def test_webhook_handle_render_template(create_registrations, webhook_clie
     """Test that we render templates properly."""
     resp = await webhook_client.post(
         "/api/webhook/{}".format(create_registrations[1]["webhook_id"]),
-        json=RENDER_TEMPLATE,
+        json={
+            "type": "render_template",
+            "data": {
+                "one": {"template": "Hello world"},
+                "two": {"template": "{{ now() | random }}"},
+                "three": {"template": "{{ now() 3 }}"},
+            },
+        },
     )
 
     assert resp.status == 200
 
     json = await resp.json()
-    assert json == {"one": "Hello world"}
+    assert json == {
+        "one": "Hello world",
+        "two": {"error": "TypeError: object of type 'datetime.datetime' has no len()"},
+        "three": {
+            "error": "TemplateSyntaxError: expected token 'end of print statement', got 'integer'"
+        },
+    }
 
 
 async def test_webhook_handle_call_services(hass, create_registrations, webhook_client):