Access to previous and current state in `platform: state` sensor template

nazar-pc · January 16, 2023, 2:46am

I wanted to create some sensor templates that respond to changes of other sensors (so that I don’t generate them more frequently than source data change, however I found platform: state for sensors surprisingly useless.

The core issue is that when I define entity ID to track state of, when state does actually change, there is no access (or maybe I don’t know how to get there, wasn’t able to find that in documentation) to either from or to of the change. It would be really helpful to get access to from.state, from.last_updated, from.last_changed, etc. and for the to.* as well.

Without this I’m currently storing values in attributes, which is awkward and redundant.

Didgeridrew · January 16, 2023, 4:39am

It’s a little unclear what you are asking. What is a "platform: state sensor template"? Do you mean a trigger-based template sensor?

For trigger-based template sensors, you have access to all the same available trigger data you can get in automations by using the trigger variable.

123 · January 16, 2023, 4:48am

Seems to be related to this:

github.com/home-assistant/core

last_updated in template sensor is updated before computing state

opened 02:30AM - 16 Jan 23 UTC

nazar-pc

integration: template

### The problem I have a template sensor, the idea of which is to track the ave…rage amount of power flowing into the battery over period of time and compute stored energy from that. However it doesn't work like expected since `last_updated` of the sensor itself is updated right before computing state (~0.09 seconds ago), resulting in ridiculous values and inability to compute the time difference. It would make sense to me to compute all the templates in a sensor and only then update the time difference. ### What version of Home Assistant Core has the issue? 2023.1.1 ### What was the last working version of Home Assistant Core? _No response_ ### What type of installation are you running? Home Assistant OS ### Integration causing the issue template ### Link to integration documentation on our website https://www.home-assistant.io/integrations/template ### Diagnostics information _No response_ ### Example YAML snippet ```yaml - sensor: - name: "Stored battery energy" unique_id: stored_battery_energy state_class: total_increasing unit_of_measurement: kWh device_class: energy attributes: battery_power_value: > {{ states('sensor.battery_power') | float(0) }} state: > {% set current_battery_power_value = max(0, states('sensor.battery_power') | float(0)) %} {% set old_battery_power_value = state_attr('sensor.stored_battery_energy', 'battery_power_value') %} {% if old_battery_power_value != None -%} {% set old_battery_power_value = max(0, old_battery_power_value | float) %} {% set average_power = (current_battery_power_value + old_battery_power_value) / 2 %} {% set time_delta = (as_timestamp(now()) - as_timestamp(states.sensor.stored_battery_energy.last_updated)) / 3600 %} {% set added_energy_value = time_delta * average_power / 1000 | round(3, default=0) %} {{ states('sensor.stored_battery_energy') | float + added_energy_value }} {%- else -%} 0 {%- endif %} ``` ### Anything in the logs that might be useful for us? _No response_ ### Additional information I already had to store `battery_power_value` attribute because `platform: state` doesn't seem to provide `from` and `to` values of the state change, now I'll have to store time explicitly in an attribute as well to work around this bug.

nazar-pc · January 18, 2023, 10:48am

Hm… I did actually look there and something didn’t work, but now I tried it and succeeded. Thanks!

Would have been great to have more links back and forth between all those pages. Like when I see the trigger, the next thing I want to know is that data it contains.

nazar-pc · January 18, 2023, 10:49am

It is an unexpected behavior I discovered when working around what I thought didn’t work. I think it is of a separate value and should be fixed.

123 · January 18, 2023, 2:26pm

I would expect the value of last_updated to be the previous time when it was updated (not the current time while it’s being updated). So I agree it should be corrected.