Isolating a value from a json array

Hi, i got a rest sensor that gives me the following output:

[{"uuid":"c597f74b-c217-e811-80c2-000d3ab14a80","hasDefaultValues":false,"name":"Stue","nodeUuid":"c497f74b-c217-e811-80c2-000d3ab14a80","targetTemperature":19.0}]

i’m looking to extract only the targetTemperature property, but the following doesnt seem to work:

"{{ value_json[0].targetTemperature }}"

It is giving me a

Error rendering template: UndefinedError: value_json is undefined

Any ideas?

What about?
{{ value[0].targetTemperature }}

Getting the following:

Error rendering template: UndefinedError: ‘value’ is undefined

Please post the config of your rest sensor.

- platform: rest
  name: ngenic
  resource: https://app.ngenic.se/api/v3/tunes/XXXXXXX/rooms
  headers:
    Authorization: Bearer XXXXXXX

Shoudn’t the configuration of your RESTful sensor contain a value_template?

  value_template: "{{ value_json[0].targetTemperature }}"

Thanks, that solved it!

I originally had the value_template in there, but removed it in order to get the full payload into HA so i could experiement in the template editor.