[SOLVED] How to cope with special characters in JSON MQTT values

Configuration
1

Just wanted to put this here for future reference:

I have a smartmeter that enacpsulates its data over MQTT in JSON like so:

{
  "timestamp":"23.10.2023 22:12:36",
  "+A":77.205,
  "-A":0,
  "+R":2.152,
  "-R":185.659,
  "+P":647,
  "-P":0,
  "+Q":7,
  "-Q":204
}

using this in a sensor like this:

    - name: "energy_P"
      unique_id: "energy_P"
      state_topic: "house/smartmeter/state"
      unit_of_measurement: "W"
      value_template: "{{ value_json.+P }}"

just gives an error on the last line, because “value_json.+P” does not parse correctly.
But since “value_json” is a dictionary, we can write

      value_template: "{{ value_json['+P'] }}"

instead and it works fine!
(Note the single quotes, since double quotes are already used on the outside!)

1 Like
2

Bracket notation is always safer than dot notation.

3

Welcome!

and welcome to the ‘wonderful’ world of jinja2 and JSON parsing… Two good examples why to combine Home Automation with liberal quantities of :wine_glass: and/or :beer: makes ‘sensor’ sense…