Add topic_template for mqtt.publish (#53743)

Co-authored-by: Erik Montnemery <erik@montnemery.com>

Co-authored-by: Erik Montnemery <erik@montnemery.com>

homeassistant/components/mqtt/__init__.py

@@ -106,6 +106,7 @@ DEFAULT_KEEPALIVE = 60
 DEFAULT_PROTOCOL = PROTOCOL_311
 DEFAULT_TLS_PROTOCOL = "auto"
 
+ATTR_TOPIC_TEMPLATE = "topic_template"
 ATTR_PAYLOAD_TEMPLATE = "payload_template"
 
 MAX_RECONNECT_WAIT = 300  # seconds
@@ -220,15 +221,19 @@ MQTT_RW_PLATFORM_SCHEMA = MQTT_BASE_PLATFORM_SCHEMA.extend(
 )
 
 # Service call validation schema
-MQTT_PUBLISH_SCHEMA = vol.Schema(
-    {
-        vol.Required(ATTR_TOPIC): valid_publish_topic,
-        vol.Exclusive(ATTR_PAYLOAD, CONF_PAYLOAD): cv.string,
-        vol.Exclusive(ATTR_PAYLOAD_TEMPLATE, CONF_PAYLOAD): cv.string,
-        vol.Optional(ATTR_QOS, default=DEFAULT_QOS): _VALID_QOS_SCHEMA,
-        vol.Optional(ATTR_RETAIN, default=DEFAULT_RETAIN): cv.boolean,
-    },
-    required=True,
+MQTT_PUBLISH_SCHEMA = vol.All(
+    vol.Schema(
+        {
+            vol.Exclusive(ATTR_TOPIC, CONF_TOPIC): valid_publish_topic,
+            vol.Exclusive(ATTR_TOPIC_TEMPLATE, CONF_TOPIC): cv.string,
+            vol.Exclusive(ATTR_PAYLOAD, CONF_PAYLOAD): cv.string,
+            vol.Exclusive(ATTR_PAYLOAD_TEMPLATE, CONF_PAYLOAD): cv.string,
+            vol.Optional(ATTR_QOS, default=DEFAULT_QOS): _VALID_QOS_SCHEMA,
+            vol.Optional(ATTR_RETAIN, default=DEFAULT_RETAIN): cv.boolean,
+        },
+        required=True,
+    ),
+    cv.has_at_least_one_key(ATTR_TOPIC, ATTR_TOPIC_TEMPLATE),
 )
 
 
@@ -450,11 +455,36 @@ async def async_setup_entry(hass, entry):
 
     async def async_publish_service(call: ServiceCall):
         """Handle MQTT publish service calls."""
-        msg_topic: str = call.data[ATTR_TOPIC]
+        msg_topic = call.data.get(ATTR_TOPIC)
+        msg_topic_template = call.data.get(ATTR_TOPIC_TEMPLATE)
         payload = call.data.get(ATTR_PAYLOAD)
         payload_template = call.data.get(ATTR_PAYLOAD_TEMPLATE)
         qos: int = call.data[ATTR_QOS]
         retain: bool = call.data[ATTR_RETAIN]
+        if msg_topic_template is not None:
+            try:
+                rendered_topic = template.Template(
+                    msg_topic_template, hass
+                ).async_render(parse_result=False)
+                msg_topic = valid_publish_topic(rendered_topic)
+            except (template.jinja2.TemplateError, TemplateError) as exc:
+                _LOGGER.error(
+                    "Unable to publish: rendering topic template of %s "
+                    "failed because %s",
+                    msg_topic_template,
+                    exc,
+                )
+                return
+            except vol.Invalid as err:
+                _LOGGER.error(
+                    "Unable to publish: topic template '%s' produced an "
+                    "invalid topic '%s' after rendering (%s)",
+                    msg_topic_template,
+                    rendered_topic,
+                    err,
+                )
+                return
+
         if payload_template is not None:
             try:
                 payload = template.Template(payload_template, hass).async_render(

tests/components/mqtt/test_init.py

@@ -150,6 +150,103 @@ async def test_service_call_without_topic_does_not_publish(hass, mqtt_mock):
     assert not mqtt_mock.async_publish.called
 
 
+async def test_service_call_with_topic_and_topic_template_does_not_publish(
+    hass, mqtt_mock
+):
+    """Test the service call with topic/topic template.
+
+    If both 'topic' and 'topic_template' are provided then fail.
+    """
+    topic = "test/topic"
+    topic_template = "test/{{ 'topic' }}"
+    with pytest.raises(vol.Invalid):
+        await hass.services.async_call(
+            mqtt.DOMAIN,
+            mqtt.SERVICE_PUBLISH,
+            {
+                mqtt.ATTR_TOPIC: topic,
+                mqtt.ATTR_TOPIC_TEMPLATE: topic_template,
+                mqtt.ATTR_PAYLOAD: "payload",
+            },
+            blocking=True,
+        )
+    assert not mqtt_mock.async_publish.called
+
+
+async def test_service_call_with_invalid_topic_template_does_not_publish(
+    hass, mqtt_mock
+):
+    """Test the service call with a problematic topic template."""
+    await hass.services.async_call(
+        mqtt.DOMAIN,
+        mqtt.SERVICE_PUBLISH,
+        {
+            mqtt.ATTR_TOPIC_TEMPLATE: "test/{{ 1 | no_such_filter }}",
+            mqtt.ATTR_PAYLOAD: "payload",
+        },
+        blocking=True,
+    )
+    assert not mqtt_mock.async_publish.called
+
+
+async def test_service_call_with_template_topic_renders_template(hass, mqtt_mock):
+    """Test the service call with rendered topic template.
+
+    If 'topic_template' is provided and 'topic' is not, then render it.
+    """
+    await hass.services.async_call(
+        mqtt.DOMAIN,
+        mqtt.SERVICE_PUBLISH,
+        {
+            mqtt.ATTR_TOPIC_TEMPLATE: "test/{{ 1+1 }}",
+            mqtt.ATTR_PAYLOAD: "payload",
+        },
+        blocking=True,
+    )
+    assert mqtt_mock.async_publish.called
+    assert mqtt_mock.async_publish.call_args[0][0] == "test/2"
+
+
+async def test_service_call_with_template_topic_renders_invalid_topic(hass, mqtt_mock):
+    """Test the service call with rendered, invalid topic template.
+
+    If a wildcard topic is rendered, then fail.
+    """
+    await hass.services.async_call(
+        mqtt.DOMAIN,
+        mqtt.SERVICE_PUBLISH,
+        {
+            mqtt.ATTR_TOPIC_TEMPLATE: "test/{{ '+' if True else 'topic' }}/topic",
+            mqtt.ATTR_PAYLOAD: "payload",
+        },
+        blocking=True,
+    )
+    assert not mqtt_mock.async_publish.called
+
+
+async def test_service_call_with_invalid_rendered_template_topic_doesnt_render_template(
+    hass, mqtt_mock
+):
+    """Test the service call with unrendered template.
+
+    If both 'payload' and 'payload_template' are provided then fail.
+    """
+    payload = "not a template"
+    payload_template = "a template"
+    with pytest.raises(vol.Invalid):
+        await hass.services.async_call(
+            mqtt.DOMAIN,
+            mqtt.SERVICE_PUBLISH,
+            {
+                mqtt.ATTR_TOPIC: "test/topic",
+                mqtt.ATTR_PAYLOAD: payload,
+                mqtt.ATTR_PAYLOAD_TEMPLATE: payload_template,
+            },
+            blocking=True,
+        )
+    assert not mqtt_mock.async_publish.called
+
+
 async def test_service_call_with_template_payload_renders_template(hass, mqtt_mock):
     """Test the service call with rendered template.