Fix webhook exception when empty json data is sent (home-assistant#158254)

Author: mikedast

homeassistant/components/webhook/trigger.py

@@ -15,6 +15,7 @@
 from homeassistant.helpers.template import Template
 from homeassistant.helpers.trigger import TriggerActionType, TriggerInfo
 from homeassistant.helpers.typing import ConfigType, TemplateVarsType
+from homeassistant.util.json import json_loads
 
 from . import (
     DEFAULT_METHODS,
@@ -62,7 +63,9 @@ async def _handle_webhook(
     base_result: dict[str, Any] = {"platform": "webhook", "webhook_id": webhook_id}
 
     if "json" in request.headers.get(hdrs.CONTENT_TYPE, ""):
-        base_result["json"] = await request.json()
+        #  Always attempt to read the body; request.text() returns "" if empty
+        text = await request.text()
+        base_result["json"] = json_loads(text) if text else {}
     else:
         base_result["data"] = await request.post()
 

tests/components/webhook/test_trigger.py

@@ -8,6 +8,7 @@
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.setup import async_setup_component
 
+from tests.common import async_capture_events
 from tests.typing import ClientSessionGenerator
 
 
@@ -377,3 +378,46 @@ def store_event(event):
 
     assert len(events) == 1
     assert events[0].data["hello"] == "yo world"
+
+
+async def test_webhook_query_json_header_no_payload(
+    hass: HomeAssistant, hass_client_no_auth: ClientSessionGenerator
+) -> None:
+    """Test requests with application/json header but no payload."""
+    events = async_capture_events(hass, "test_success")
+
+    assert await async_setup_component(
+        hass,
+        "automation",
+        {
+            "automation": {
+                "trigger": {
+                    "platform": "webhook",
+                    "webhook_id": "no_payload_webhook",
+                    "local_only": True,
+                    "allowed_methods": ["GET", "POST"],
+                },
+                "action": {
+                    "event": "test_success",
+                },
+            }
+        },
+    )
+    await hass.async_block_till_done()
+    client = await hass_client_no_auth()
+
+    # GET
+    response = await client.get(
+        "/api/webhook/no_payload_webhook", headers={"Content-Type": "application/json"}
+    )
+    await hass.async_block_till_done()
+    assert response.status == 200
+
+    # POST
+    response = await client.post(
+        "/api/webhook/no_payload_webhook", headers={"Content-Type": "application/json"}
+    )
+    await hass.async_block_till_done()
+    assert response.status == 200
+
+    assert len(events) == 2