Add new retain configuration option.

Author: mjmccans

CHANGELOG.md

@@ -1,3 +1,7 @@
+## [1.0.2] - 2022-02-13
+### New
+* New configuration option to retain your sensor values in the MQTT broker.
+
 ## [1.0.1] - 2022-04-08
 ### Fixes
 * Updated documentation and added check for Mosquitto MQTT broker addon requirement.

README.md

@@ -105,6 +105,11 @@ The `log_level` option controls the level of log output by the add-on and can be
 This option controls whether the Home Assistant's MQTT Discovery feature is enabled or disabled. If disabled, you can configure the sensors individually and they will be located at mqtt topic `/airthings/<mac>/<sensor name>` where <mac> is the `mac` address you set for your device and `sensor name` is the name of the sensor from the device. For example, the sensor names for the Airthings Wave Plus are: `humidity`, `radon_1day_avg`, `radon_longterm_avg`, `temperature`, `rel_atm_pressure`, `co2` and `voc`.
 
 
+### Option: `retain`
+
+This option sets the "retain" flag for the sensor values sent to the MQTT broker. This means that the last sensor value will be retained by the MQTT broker, meaning that if you restart Home Assistant the last sensor values sent to the MQTT broker will show up immediately once Home Assistant restarts. The downside is that the sensor values may be out of date, particularly if the add-on has stopped. If you change this value to "false" the add-on will clear any existing retained values.
+
+
 ## Current Limitations
 
 * This add-on has only been tested with a single Airthings Wave Plus device, but should work with multiple devices

config.yaml

@@ -1,5 +1,5 @@
 name: Airthings
-version: 1.0.1
+version: 1.0.2
 slug: airthings
 description: Read sensor values from Airthings Wave environmental monitoring devices
 url: https://github.com/mjmccans/hassio-addon-airthings
@@ -25,6 +25,7 @@ options:
   retry_wait: 3
   log_level: INFO
   mqtt_discovery: "true"
+  retain: "false"
 schema:
   devices:
     - mac: str?
@@ -34,4 +35,5 @@ schema:
   retry_wait: int
   log_level: str
   mqtt_discovery: bool
+  retain: bool?
 image: mjmccans/hassio-addon-airthings-{arch}

src/airthings-mqtt.ha.py

@@ -30,7 +30,7 @@
 CONFIG = {}     # Variable to store configuration
 DEVICES = {}    # Variable to store devices
 
-# Sensor detail deafults (for MQTT discovery)
+# Sensor detail defaults (for MQTT discovery)
 SENSORS = {
     "radon_1day_avg": {"name": "Radon (1 day avg.)", "device_class": None, "unit_of_measurement": "Bq/m3", "icon": "mdi:radioactive", "state_class": "measurement"},
     "radon_longterm_avg": {"name": "Radon (longterm avg.)", "device_class": None, "unit_of_measurement": "Bq/m3", "icon": "mdi:radioactive", "state_class": "measurement"},
@@ -211,7 +211,7 @@ def mqtt_publish(msgs):
     CONFIG["mqtt"]["host"] = vars(args)['host']
     CONFIG["mqtt"]["port"] = vars(args)['port']
     CONFIG["mqtt"]["username"] = vars(args)['username']
-    CONFIG["mqtt"]["password"] = vars(args)['password']    
+    CONFIG["mqtt"]["password"] = vars(args)['password']
 
     # Set logging level (defaults to INFO)
     if CONFIG["log_level"] in ["CRITICAL", "ERROR", "WARNING", "INFO", "DEBUG"]:
@@ -280,7 +280,6 @@ def mqtt_publish(msgs):
                 _LOGGER.info("Done sending HA mqtt discovery configuration messages.")
                 msgs = []
                 time.sleep(5)
-                first = False
 
             # Collect all of the sensor data
             _LOGGER.info("Collecting sensor value messages...")
@@ -298,10 +297,17 @@ def mqtt_publish(msgs):
                             else:
                                 val = round(val)
                         _LOGGER.info("{} = {}".format("airthings/"+mac+"/"+name, val))
-                        msgs.append({'topic': "airthings/"+mac+"/"+name, 'payload': val})
+                        
+                        # If this is a first run, clear any retained messages if "retained" is not set in config.
+                        if first and not CONFIG["retain"]:
+                            _LOGGER.debug("Appending message to delete any existing retained message...")
+                            msgs.append({'topic': "airthings/"+mac+"/"+name, 'payload': '', 'retain': True})
+                        
+                        msgs.append({'topic': "airthings/"+mac+"/"+name, 'payload': val, 'retain': CONFIG["retain"]})
 
             # Publish the sensor data to mqtt broker
             mqtt_publish(msgs)
+            first = False
         else:
             _LOGGER.error("\033[31mNo sensor values collected. Please check your configuration and make sure your bluetooth adapter is available. If the watchdog option is enabled, this addon will restart and try again.\033[0m")
             sys.exit(1)