Ive been using this for the last week, and it works just fine (though I had an interrupt upon first restart ;-0
I just can not be sure I fully understand the state template, more specifically the iif section. Could you please explain what that does and why? Why is the ‘shutdown’ also listed in thehomeassistant_started if?
When Home Assistant is shutdown gracefully, the sensor sets its state to shutdown.
On startup, the sensor checks its previous state.
If it was shutdown, it changes its state to start.
If it was not shutdown, it changes its state to interrupt.
So if Home Assistant is not shutdown gracefully, the sensor never gets a chance to set its state to shutdown. It’s state remains as start (or unknown). On startup, the sensor detects that its previous state was not shutdown and reports interrupt.
IF Home Assistant just started
THEN
IF my previous state was 'shutdown' (if I had no previous state then use 'unknown')
THEN
Set my state to 'start'
ELSE
Set my state to 'interrupt'
ELSE
Set my state to 'shutdown'
thanks for that last bit, because that (and the use of the ‘==’ operator) was what I am struggling with, especially given what is said in the warning box under:Templating - Home Assistant
What it’s warning against is that it doesn’t care if the result of the test is true or false, it will always compute the values of if_true, if_false, and if_none.
This will work:
{{ x + 3 if x is defined else 3 }}
This will fail because it will attempt to evaluate x + 3 even when x is undefined.
{{ iif(x is defined, x + 3, 3) }}
The template I posted above isn’t affected by this behaviour because the values of its if_true and if_false are just strings.
thanks again Taras, that explains it very well.
I must admit I was thrown off by the ‘==’ and was looking for a closing ), but now see that the full
this.state|default('unknown') == 'shutdown'
compares to the
is_state('light.kitchen', 'on')
from the docs in the first iif example jut above that warning boxs…
btw, adding a unique_id to that trigger template makes it UI configurable, and I tried to create an extra on/off attribute, so we could easily use that in an automation trigger. Never sure if it updates to the latest state though, so I made this separate binary and that seems to operate correctly:
using a first time name during creation, and next commenting that, so the UI can take over.
note ‘interrupt’ at first launch/creation, and binary on, even though state is interrupt…? I have taken out the device_class afterwards though, as it is a positive binary, meaning ‘on’ is good…:
yes, you are right.
I tend to create these binary ‘alerts’ so I can easily make frontend conditionals on those too, not only trigger automations. Even use those binary alerts in a container UI binary consisting of only binary_sensors…
but again, maybe I am overdoing things, and I could take several of these out. will scrutinize to see if deletion will bring me (back) some extra efficiency gain.
thanks anyways, its a very fine example of trigger based template and iif usage.
Should be in the docs!
@123 Even after multiples tries and reading of explanations, a plain copy/paste of the above code snippet doesn’t work : in the history attribute, I only see homeassistant_started events, no single homeassistant_stop events.
What could be missing to have it running like expected ?
I have performed a test and was able to replicate your results. There’s no record of the sensor being able to detect Home Assistant’s homeassistant_stop event.
I modified the sensor’s code to use Homeassistant Trigger to detect the shutdown event but it still failed to detect it
- platform: homeassistant
event: shutdown
It appears that since I posted my example in March, something changed in Home Assistant that now prevents a Trigger-based Template Sensor from detecting any events involving the shutdown process.
It seems like a bug. I wish I knew what changed that caused a Trigger-based Template entity to lose the ability to detect the shutdown event. Maybe the Template integration is already disabled by the time the shutdown event is fired.
I tested 3 workarounds:
1 - Automation + MQTT: Create an MQTT sensor and update/check its status using start/shutdown events.
Problem: the sensor is not being read at start, despite the MQTT state being correct, the sensor remains unknown, causing the automation to set the state to interrupted. Any idea?
2 - Automation + text helper: Same logic as above.
Problem: Strange behavior, it always returns to the state before it was shutdown, it seems that the state set by the automation is not persistent.
3 - Automation + shell command + python_script:
It seems to be working well:
It seems that homeassistant_stop event works again, at least in 2023.12.1.
There is one more caveat when using a template sensor, though. Home Assistant itself does not immediately write the new sensor state to the disk after it has been changed (e.g. set to start after a graceful reboot). If a power failure happens at this moment, upon the next startup the state of the sensor will be start instead of ‘interrupt’ because the recent stored value in entity registry was shutdown.
can confirm this to work (note I added a trigger.id as there are no trigger variables to the homeassistant platform to use?). See the top 2 attributes in the screen tp be the result of this latest version:
Hi Marius,
Thanks for making this suggestion.
I have implemented your exact code but the state never reaches “interrupt” even though I just pull the plug on the power supply.
Also it seems your screenshot with history does not match the above code since it shows “event: stop” but the trigger ids only include “start” and “shutdown”. Just curious?
In my case, I seem to get a shutdown state briefly before the start state and this causes the interrupt to not be triggered. When I do normal reboot, the shutdown state duration is about 1 min - 1.5 min, but when I just pull the plug on the power supply and then connect it, I still get a shutdown state but it only lasts around 20 sec.
Any idea why this happens? And is anyone else seeing this behavior?
hmm, seems you are right… tbh, I hadn’t even realized that, and cant remember now how that would have been an option before, I need to go to the backups of that time.
@emkaywest just read the thread above, on the change of the trigger events. The previous screenshot I posted was made when the former events still were like that.