Gold standard: avoid template sensors falling to zero

Configuration
1

For many template sensors (used for statistics or the energy dashboard) it is important to avoid their values falling to zero, especially/e. g. if this is not possible in reality (e. g. because it’s a total_increase sensor or whatever).

While I managed to set up percentage sensors correctly (they do basic calculations - basically transferring absolute sensor values to percentage values), I struggle with others and I’m wondering what’s the “one size fits all” solution, the gold standard of achieving this.

E. g. this one is based on a group. On every reload of groups this sensor falls to zero…

grafik

…even I meanwhile have double and triple checks to avoid this aaaaand an availability template:

template:
  - sensor:
      - name: Problematische Entitäten (ignorierte) Anzahl
        # entity_id: problems_any_ignored_count
        unique_id: xxxxxx-something-xxxxxx
        state_class: total
        icon: mdi:numeric
        #state: "{{ expand(states.group.problems_any_ignored) | length }}"
        state: >-
          {% if (expand(states.group.problems_any_ignored) | length) | int(0) == 0 %}
          {% else %}
            {% if (expand(states.group.problems_any_ignored) | length) | int(0) > 0 %}
              {{ expand(states.group.problems_any_ignored) | length }}
            {% endif %}
          {% endif %}
        availability: "{{ (expand(states.group.problems_any_ignored) | length) | int(0) > 0) }}"

…but still, every group reload (which is just ONE but a nice trigger cause I can provocate it nicely) gives this in the database (states table) and of course renders graphs unusable:

state_id 	domain 	entity_id 							state 	attributes 	event_id 	last_changed 				last_updated 				created 	old_state_id 	attributes_id
65885671 	NULL 	sensor.problems_any_ignored_count 	31 		NULL 		67523426 	2022-06-01 00:09:12.928600 	2022-06-01 00:09:12.928600 	NULL 		65885652 		478
65885652 	NULL 	sensor.problems_any_ignored_count 	0 		NULL 		67523407 	2022-06-01 00:09:12.409461 	2022-06-01 00:09:12.409461 	NULL 		65885219 		478

What’s wrong here? Maybe the default of the int (int(0))?

But I’m not into a solution for this specific issue. I’m interested in general:
how do you template your sensors when it’s important to avoid them switching to zero?

2

Well I’m not sure but to start your availability template is going to have an error every time you reload groups. When you do states.group.problems_any_ignored like that then if group.problems_any_ignored doesnt exist you get an exception (and it won’t exist while groups are reloading) since you’re trying to access a non-existent key of an object.

Its much safer to replace your expands with this

expand('group.problems_any_ignored')

It does the same thing but won’t have an exception if the group doesn’t exist.

I dont know for certain if that will fix your issue since I honestly don’t know what happens if your availability template has an exception. I use those to prevent exceptions and go to great lengths to avoid causing them there.

3

Thanks, I adjusted all group expand syntax. Unfortunately, that makes no difference. So I’m still lost (but at least learned a bit already).

4

Had a similar problem and fixed it by applying the outlier filter:

I had a scrape sensor that would return zero every once in a while, because it could not get the data from the website.
With the filter i let the algo look at the last 3 values and if the new value is more than xxx away from that value it is ignored and the sensor does no longer return zero.

5

That’s an interesting filter.

Just wanted to follow-up:

  • The original issue has been resolved with a HA Core update meanwhile (it switches to unavailable or unknown now during reload/initialization), so the sensor doesn’t “fall to zero” anymore, even when reloading:
    grafik
    grafik3679×777 206 KB

And in general I learned it’s good practise to use availability templates to filter undesired states (in case they are static and 100 % unwanted/impossible, like in my original use-case the value 0 (zero)):

availability: "{{ ((expand('group.problems_any_ignored') | length) | int(0) > 0) }}"

Checking unavailable etc.:

availability: "{{ states('sensor.abc') not in ['NULL', 'null', 'none', 'undefined', 'unavailable', 'unknown', ''] }}"

There’s also an integration providing this as a custom template integration using HACS: