Is it possible to update a JSON element within an MQTT topic?

Configuration
,
1

Currently the MQTT topic looks like this…

image
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I want to update the “May” element at month end with a new value. I’ve tried publishing this to MQTT but it wipes out the rest of the json:

service: mqtt.publish
data:
  topic: energy/sensor/car_charger_energy/history
  payload: >-
        {
          "{{ as_timestamp(now()) | timestamp_custom('%b') }}": {{ states("sensor.monthly_energy_cost_car_charger") }}
        }

image

Or do I need to change the structure of the MQTT topic???

2

I guess not…

3

pull the history in to a sensor’s attribute, then use that attribute when publishing a change to the payload.

4

Sorry @petro but I had trouble following you.
I’ve ended up with the following…

I manually published homeassistant/sensor/car_charging_energy_cost:
image

Then added this integration:

mqtt_statestream:
  base_topic: homeassistant
  publish_attributes: true
  publish_timestamps: true
  include:
    entities:
      - sensor.car_charging_energy_cost

and created this automation which hopefully populates each month and again hopefully will update a Last Year total:

alias: Update Car Charging Energy Cost History
description: ''
trigger:
  - platform: state
    entity_id:
      - select.car_charging
    from: step_2
    to: step_1
condition: []
action:
  - if:
      - condition: template
        value_template: '{{ as_timestamp(now()) | timestamp_custom("%b") == "January" }}'
    then:
      - service: python_script.set_state
        data_template:
          entity_id: sensor.car_charging_energy_cost
          Last Year: >-
            {{ state_attr("sensor.car_charging_energy_cost",
            "January")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "February")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "March")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "April")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "May")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "June")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "July")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "August")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "September")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "October")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "November")|float(default=0) + 
               state_attr("sensor.car_charging_energy_cost", "December")|float(default=0) }}
  - service: python_script.set_state
    data_template:
      entity_id: sensor.car_charging_energy_cost
      '{{ as_timestamp(now()) | timestamp_custom("%b") }}': >-
        {{ (state_attr("sensor.car_charging_step_1",
        "last_period")|float(default=0) *
        states("input_number.bchydro_step_1_rate")|float(default=0) +
        state_attr("sensor.car_charging_step_2", "last_period")|float(default=0)
        * states("input_number.bchydro_step_2_rate")|float(default=0)) |
        round(2) }}
mode: single
1 Like
5

@4331525 I abandoned that approach and went with this simple automation, once I learned about Google Sheets!

alias: 32A Car Charging
description: ""
trigger:
  - entity_id:
      - binary_sensor.32a_car_charging
    platform: state
    to: "off"
    from: "on"
condition: []
action:
  - service: input_number.set_value
    data:
      value: >-
        {{ (states('sensor.32a_car_charging_session_step_1')|float(0) *
        states('input_number.bchydro_step_1_rate')|float(0) +
        states('sensor.32a_car_charging_session_step_2')|float(0) *
        states('input_number.bchydro_step_2_rate')|float(0)) | round(2) }}
    target:
      entity_id: input_number.car_charging_cost
    enabled: true
  - service: google_sheets.append_sheet
    data:
      config_entry: 1b4a46c6cba0677bbfb5a8c53e8618b0
      worksheet: Clarity Charging
      data:
        Date: "{{ now().strftime('%-d-%b-%y') }}"
        Step 1: "{{ states('sensor.32a_car_charging_session_step_1') }}"
        Step 2: "{{ states('sensor.32a_car_charging_session_step_2') }}"
        Cost: "{{ states('input_number.car_charging_cost') }}"
  - service: input_number.set_value
    data:
      value: "{{ states('sensor.32a_car_charging_session_step_1') }}"
    target:
      entity_id: input_number.32a_car_charger_last_session_step_1
  - service: input_number.set_value
    data:
      value: "{{ states('sensor.32a_car_charging_session_step_2') }}"
    target:
      entity_id: input_number.32a_car_charger_last_session_step_2
  - service: utility_meter.reset
    data: {}
    target:
      entity_id: select.32a_car_charging_session
mode: single

I am also now using the EV Charger Card in Lovelace…

image
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