Json sensor data unknown, replace with value

Configuration
1

Hi,

I have a RESTful sensor configured, reading data from a Fronius solar inverter. The sensor is configured thus:

  - platform: rest
    resource: http://192.168.0.115/solar_api/v1/GetInverterRealtimeData.cgi?Scope=Device&DeviceId=1&DataCollection=CommonInverterData
    name: "Current Power"
    value_template: '{{ value_json.Body.Data.PAC.Value }}'
    unit_of_measurement: 'W'
    force_update: true

This works fine when the panels are generating power, but the system stops presenting the data once the sun goes away.

Is there a way, using templating, that I can use the value of the field when it is present, and return zero for the sensor value when the object returns unknown?

Any assistance will be much appreciated.

Thanks

2

Without knowing exactly what the json looks like normally it can be hard to say for sure but try something like this:

{% if value_json.Body.Data.PAC.Value is defined %}
  {{ value_json.Body.Data.PAC.Value }}
{% else %}
  0
{% endif %}
3

Ah - I wasn’t aware that you could use templated values as results of an “if” clause - none of the examples show that, only literals…

Thanks - will try it.

Edit: Actually there are heaps of examples if you look in the right place - thanks again.

4

So - checking “Value” returns an error, you need to check the level up in the tree exists - this would probably have been obvious if I supplied examples of the Json, when the panels are off the object PAC is not supplied, not just the value. The final template looks like:

   - platform: rest
     resource: http://192.168.0.115/solar_api/v1/GetInverterRealtimeData.cgi?Scope=Device&DeviceId=1&DataCollection=CommonInverterData
     name: "Current Power"
     value_template: >
         {% if value_json.Body.Data.PAC is defined %}
             {{ value_json.Body.Data.PAC.Value }}
         {% else %}
             0
         {% endif %}
     unit_of_measurement: 'W'
     force_update: true
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