Process a MQTT string only if start with a specific character

Configuration
1

Hello,
i have an esp32 with tasmota sending mqtt data to home assistant.
Home assisstant receive 2 type or strings:

10:08:40.337 MQT: tele/BatteryMonitor/RESULT = {"SSerialReceived":":R51=1,\n:r51=1,27,3000,2000,0,0,0,100,0,0,3040,100,100,100,0,0,1,\r\n"}
10:08:40.716 MQT: tele/BatteryMonitor/RESULT = {"SSerialReceived":":R50=1,\n:r50=1,243,2532,1450,77914,272348,302933,166440,129,0,99,0,334,2518,\r\n"}

I only need the R50 string and the 51 only gives me problems when home assistant process it.
This is the configuration i use to handle the mqtt (ther are other 4 sensors after this one)

  - trigger:
      - platform: mqtt
        topic: tele/BatteryMonitor/RESULT
        encoding: ""
    sensor:
      - name: BatteryMonitor-Temperatura
        unit_of_measurement: "°C"
        state: "{{ (trigger.payload.split(',')[9] | float-100) }}"

How can i configure it to only tank in consideration the R50 string and not the R51?

2

If the received payload doesn’t contain the string R51 then the template extracts the desired value. If the payload does contain the string, the template reports the sensor’s existing value (this.state).

  - trigger:
      - platform: mqtt
        topic: tele/BatteryMonitor/RESULT
        encoding: ""
    sensor:
      - name: BatteryMonitor-Temperatura
        unit_of_measurement: "°C"
        state: >
          {{ trigger.payload.split(',')[9] | float(0) - 100
            if 'R51' not in trigger.payload else this.state }}
1 Like
3

Tank you, this did not quite work because i’ve now seen that the string sometimes contain both r50 and r51.

{"SerialReceived":":R50=2,\n:r50=2,224,2531,4040,153115,390102,837886,183181,130,0,0,0,293,0,\r\n:R51=2,\n:r51=2,27,3000,2000,0,0,0,100,0,0,3040,100,100,100,0,0,1,\r\n"}

I’ve modified your code and now it’s working, it just bugs out sometimed (maybe ther is something that changes in the string that i don’t know)
This is the updated code if someone needs it

  - trigger:
      - platform: mqtt
        topic: tele/BatteryMonitor/RESULT
    sensor:
      - name: BatteryMonitor-Temperatura
        unit_of_measurement: "°C"
        state: >
          {{ (trigger.payload.split(',')[9] | float-100)
            if 'R50' in trigger.payload else this.state}}

Now, another quick quyestion. if i have this string

{"SerialReceived":":R50=2,\n:r50=2,224,2531,4040,153115,390102,837886,183181,130,0,0,0,293,0,\r\

can i force Home assistant to only read from n:r50= to 183181 or it must read until the \r?

4

That’s a very different situation from the two examples you originally provided where it was either R50 or R51 but not both. It’s understandable that the template I had suggested wouldn’t work for that situation.

May I ask why you aren’t using the Tasmota integration to receive data from the device?