Home Assistant: Sending, receiving, and using JSON data from a Template Sensor Helper

helper_sensor

{% set aggregate = namespace(
  id = None,
  class = None,
  state = None
) %}

{% set aggregate.id = 'device id' %}
{% set aggregate.class = 'device class' %}
{% set aggregate.state = 'computed state' %}

{% set ns = namespace(instance = {
  "id": aggregate.id,
  "class": aggregate.class,
  "state": aggregate.state
}) %}
{{ ns.instance | to_json(sort_keys=True) }}

template_usage

{# Guard unavailable sensor #}
{% if states('sensor.helper_sensor') == 'unavailable' %}
{% set helper_sensor_data = {"id": None, "class": None, "state": None} %}
{% else %}
{% set helper_sensor_data = states('sensor.helper_sensor') | from_json %}
{% endif %}
{##}

<center>
<h3>Device <tt>{{ helper_sensor_data.id }}</tt></h3>
<strong>Device class:</strong> <tt>{{ helper_sensor_data.class }}</tt>
<strong>Device state:</strong> <tt>{{ helper_sensor_data.state }}</tt>
</center>