mqtt check for duplicate topics

docs/configuration.rst

@@ -104,6 +104,26 @@ These input settings can be used to poll data from a Tibber bridge:
       password: "printed on bridge socket"
 
 
+Example mqtt config
+======================================
+
+MQTT topics can be configured either by providing a full topic or a topic fragment.
+With a topic fragment the resulting topic is build with the parent topic.
+The structure is ``topic prefix`` / ``device`` / ``value``.
+Providing a full topic will ignore the fragments.
+The entries for qos and retain are optional.
+
+..
+    YamlModel: OptionalMqttPublishConfig
+
+
+.. code-block:: yaml
+
+   full topic: my/full/topic
+   qos: 1
+
+
+
 Configuration Reference
 ======================================
 All possible configuration options are described here. Not all entries are created by default in the config file

src/sml2mqtt/mqtt/__init__.py

@@ -4,4 +4,4 @@
 
 # isort: split
 
-from .mqtt_obj import BASE_TOPIC, MqttObj, patch_analyze, setup_base_topic
+from .mqtt_obj import BASE_TOPIC, MqttObj, check_for_duplicate_topics, patch_analyze, setup_base_topic

src/sml2mqtt/mqtt/mqtt_obj.py

@@ -1,5 +1,5 @@
 import dataclasses
-from collections.abc import Callable
+from collections.abc import Callable, Generator
 from typing import Any, Final
 
 from sml2mqtt.__log__ import get_logger
@@ -121,6 +121,11 @@ def create_child(self, topic_fragment: str | None = None, qos: int | None = None
         child.update()
         return child
 
+    def iter_objs(self) -> Generator['MqttObj', Any, None]:
+        yield self
+        for child in self.children:
+            yield from child.iter_objs()
+
 
 BASE_TOPIC: Final = MqttObj()
 
@@ -130,3 +135,13 @@ def setup_base_topic(topic: str, qos: int, retain: bool):
     BASE_TOPIC.cfg.qos = qos
     BASE_TOPIC.cfg.retain = retain
     BASE_TOPIC.update()
+
+
+def check_for_duplicate_topics(obj: MqttObj):
+    log = get_logger('mqtt')
+
+    topics: set[str] = set()
+    for o in obj.iter_objs():
+        if (topic := o.topic) in topics:
+            log.warning(f'Topic "{topic:s}" is already configured!')
+        topics.add(topic)

src/sml2mqtt/sml_device/setup_device.py

@@ -2,6 +2,7 @@
 
 from typing import TYPE_CHECKING
 
+from sml2mqtt.mqtt import BASE_TOPIC, check_for_duplicate_topics
 from sml2mqtt.sml_value import SmlValue
 from sml2mqtt.sml_value.operations import (
     FactorOperation,
@@ -13,7 +14,6 @@
     RoundOperation,
     SequenceOperation,
     SkipZeroMeterOperation,
-    VirtualMeterOperation,
 )
 from sml2mqtt.sml_value.setup_operations import setup_operations
 
@@ -118,3 +118,6 @@ def setup_device(device: SmlDevice, frame: SmlFrameValues, cfg: SmlDeviceConfig
 
         _create_default_transformations(device.log, sml_value, frame, general_cfg)
         _create_default_filters(device.log, sml_value, general_cfg)
+
+    # Check for duplicate MQTT topics
+    check_for_duplicate_topics(BASE_TOPIC)

tests/conftest.py

@@ -91,6 +91,11 @@ def stream_reader(monkeypatch):
     return r
 
 
+@pytest.fixture(autouse=True)
+def _clear_mqtt(monkeypatch):
+    monkeypatch.setattr(sml2mqtt.mqtt.BASE_TOPIC, 'children', [])
+
+
 @pytest.fixture(autouse=True)
 def check_no_logged_error(caplog, request):
     caplog.set_level(logging.DEBUG)

tests/test_mqtt_obj.py

@@ -1,4 +1,6 @@
-from sml2mqtt.mqtt import MqttObj
+import pytest
+
+from sml2mqtt.mqtt import MqttObj, check_for_duplicate_topics
 
 
 def test_topmost(monkeypatch):
@@ -48,3 +50,16 @@ def test_child_change(monkeypatch):
     parent.cfg.retain = False
     parent.update()
     assert (child.topic, child.qos, child.retain) == ('base/child', 0, False)
+
+
+@pytest.mark.ignore_log_warnings()
+def test_check_for_duplicate_messages(caplog):
+    parent = MqttObj('base', 2, True).update()
+    parent.create_child('child')
+    parent.create_child('child')
+
+    check_for_duplicate_topics(parent)
+
+    msg = "\n".join(x.msg for x in caplog.records)
+
+    assert msg == 'Topic "base/child" is already configured!'