MQTT Sensor Update

Configuration
1

I have a couple of MQTT sensors that that the MQTT value may only change once a week and im using templating to give me a difference in days.
The issue is HA is not recalculating. I guess its because there’s no new MQTT message being published?

sensor:

      - platform: mqtt
        name: Backup State Janet
        state_topic: 'backup/sensor/janet'
        value_template: "{{ ((as_timestamp(now()) - as_timestamp(value_json.backupTimestamp)) / 86400) | round(2) }}"
        force_update: true
        unit_of_measurement: 'Days'
        json_attributes_topic: 'backup/sensor/janet'

Is there a sensible way of forcing HA to recalculate days? The only workaround can think of is to grab the MQTT data and publish it again but feel like I may be missing something simpler.

2

Wouldn’t it perform the calculation only when it receives a message published to backup/sensor/janet? If the message arrives once a week, the calculation will only happen once a week.

Or are you saying it doesn’t perform the calculation even when it receives a new message?

3

No it preforms the calculation when HA is restarted or the MQTT message is received. Which I guess is how its supposed to work.

4

Yup! Effectively, the sensor’s value won’t change until the receipt of the next payload (a week later; or upon rebooting but hopefully that’s infrequent and not a requirement of daily operations).

5

The message is retained so I guess I use node red or an automation to read the data or sensor and republish it just after midnight everyday.

Thanks for your help

6

Update in case anyone else trips over this post.
I have worked out the best way (for me anyway) was a Node Red flow to read the sensor attributes and use them to publish a new MQTT message. This is scheduled to run every 6 hours