Return no data on template if source null

Configuration
1

I have a template that converts a ultrasonic sensor’s reading to a water level percentage:

sensor:
  - platform: template
    sensors:
      rainwater_tank_percentage:
        friendly_name: "Rainwater Tank Percentage"
        unit_of_measurement: "%"
        value_template: >-
          {% set total_height = 1.9 %}
          {% set distance = states('sensor.esphome_web_6d522e_water_level')|float(2) %}
          {% set distance_abs = distance - 0.181 |float(2) %}
          {% set fullness = distance_abs / total_height|float(2) %}
          {{ '%.0f' | format((1-fullness)*100) | float(2)}}

The problem is sometimes the ultrasonic esp32 sensor goes offline but the template still creates “data” causing crazy spikes in my graph. Is there a way to return “NULL” if the source is NULL?

image
image344×891 11.1 KB

The top graph is the calculated “template” and the bottom is the raw ultrasonic sensor, which have gaps, which is good.

2 
template:
  - sensor:
      - name: "Rainwater Tank Percentage"
        unit_of_measurement: "%"
        state_class: measurement
        state: >
          {% set total_height = 1.9 %}
          {% set distance = states('sensor.esphome_web_6d522e_water_level')|float %}
          {% set distance_abs = distance - 0.181 %}
          {% set fullness = distance_abs / total_height %}
          {{ '%.0f' | format((1-fullness)*100) }}
        availability: "{{ has_value('sensor.esphome_web_6d522e_water_level') }}"
1 Like
3

Thank you kindly, am I right in saying this will only affect future data?

4

Yes.