Allow to omit the payload attribute to MQTT publish action to allow an empty payload to be sent by default (#137595)

Allow to omit the payload attribute to MQTT publish actionto allow an empty payload to be sent by default

homeassistant/components/mqtt/__init__.py

@@ -236,7 +236,7 @@ CONFIG_SCHEMA = vol.Schema(
 MQTT_PUBLISH_SCHEMA = vol.Schema(
     {
         vol.Required(ATTR_TOPIC): valid_publish_topic,
-        vol.Required(ATTR_PAYLOAD): cv.string,
+        vol.Required(ATTR_PAYLOAD, default=None): vol.Any(cv.string, None),
         vol.Optional(ATTR_EVALUATE_PAYLOAD): cv.boolean,
         vol.Optional(ATTR_QOS, default=DEFAULT_QOS): valid_qos_schema,
         vol.Optional(ATTR_RETAIN, default=DEFAULT_RETAIN): cv.boolean,

homeassistant/components/mqtt/services.yaml

@@ -8,7 +8,6 @@ publish:
       selector:
         text:
     payload:
-      required: true
       example: "The temperature is {{ states('sensor.temperature') }}"
       selector:
         template:

homeassistant/components/mqtt/strings.json

@@ -246,11 +246,7 @@
         },
         "payload": {
           "name": "Payload",
-          "description": "The payload to publish."
-        },
-        "payload_template": {
-          "name": "Payload template",
-          "description": "Template to render as a payload value. If a payload is provided, the template is ignored."
+          "description": "The payload to publish. Publishes an empty message if not provided."
         },
         "qos": {
           "name": "QoS",

tests/components/mqtt/test_init.py

@@ -391,6 +391,25 @@ async def test_service_call_with_ascii_qos_retain_flags(
         blocking=True,
     )
     assert mqtt_mock.async_publish.called
+    assert mqtt_mock.async_publish.call_args[0][1] == ""
+    assert mqtt_mock.async_publish.call_args[0][2] == 2
+    assert not mqtt_mock.async_publish.call_args[0][3]
+
+    mqtt_mock.reset_mock()
+
+    # Test service call without payload
+    await hass.services.async_call(
+        mqtt.DOMAIN,
+        mqtt.SERVICE_PUBLISH,
+        {
+            mqtt.ATTR_TOPIC: "test/topic",
+            mqtt.ATTR_QOS: "2",
+            mqtt.ATTR_RETAIN: "no",
+        },
+        blocking=True,
+    )
+    assert mqtt_mock.async_publish.called
+    assert mqtt_mock.async_publish.call_args[0][1] is None
     assert mqtt_mock.async_publish.call_args[0][2] == 2
     assert not mqtt_mock.async_publish.call_args[0][3]