How to refresh a calculated template value?

Configuration
1

Hello,
I created a template with a countdown to show me the number of days till the event will happen.
Therefor I have a Calendar Entity connected via a google calendar:

calendar.grune_tonne	on	message: Bio in xxx
all_day: true
start_time: 2020-02-20 00:00:00
end_time: 2020-02-21 00:00:00
location: xxx; yyy
description: 
offset_reached: false
friendly_name: Grüne Tonne

And here is my template definition in configuration.yaml

next_grunetonne:
  friendly_name: Termin Grüne Tonne
  value_template: "{{ (( as_timestamp(states.calendar.grune_tonne.attributes.start_time) - as_timestamp(now()) ) / 86400 + 0.5 ) | round(0) }}"

The calculation works perfectly. But only if I restart the server. If I wait one day the calculated day stays on the day before.
How can I refresh the calculation automatically?

I saw already the hint to use homeassistant.update_entity, but I can’t see how to integrate this if I want to update the value just once a day.

thanks
Joerg

2

I’d create a time sensor if you did not already do this and then use it in your template like this:

next_grunetonne:
  friendly_name: Termin Grüne Tonne
  entity_id: sensor.time
  value_template: "{{ (( as_timestamp(states.calendar.grune_tonne.attributes.start_time) - as_timestamp(now()) ) / 86400 + 0.5 ) | round(0) }}"

This way, the template will be evaluated every minute.
You could also write an automation that updates the entity every night, up to you.

1 Like
3

Ah, thanks.
I see how it should work. I will implement it and reply later how it works.
Joerg

4

Hi Buningstone,
I think it is very close. Last night I tried to do this, just with sensor.date. I thought it might be better to save performance of the server.
The calculation was refreshed as expected, but the date (states.calendar.grune_tonne.attributes.start_time) should have been refreshed as well, but stayed at the date before.
I will switch to sensor.time and wait for the next week, when the calendar event date will change again.
But thanks so far.
Joerg

5

Why should the start time of the calendar.grune_tonne be changed as well? The calendar entry doesn’t change when a new day starts.

6

The calendar entry alway point the next event. Yesterday it pointed to yesterday. The next event is at March 3rd.
So at night start_time switched from
2020-02-18 00:00:00
to
2020-03-03 00:00:00
It should have calculated with March, but the result was “-1”, which indicates it calculated with the day before.

7

Something like this:

      bom_forecast_2:
        entity_id:
          - sensor.bom_gosford_max_temp_c_2
        friendly_name_template: >

With your template. This will force the template to be re-evaluated every time the sensor.bom_gosford_max_temp_c_2 updates which is pretty much what you want (using your sensor of course)

8

I could imagine, that the sensor.date changed before the calendar updated the start time and therefore the template still used the old value.

9

I did a test this morning with a calendar event just for test purposes. (Don’t know why I have waited a night - stupid).
Everything was setup with sensor.time
Right after one or two minutes all template values were refreshed as expected.

But I figured out one trap: After deleting the test events in my google-calendar, all values stayed at the test event.
Reason: the google calendar connector seems to look at the events in the paper bin as well. After cleaning the paper bin, the events were back to normal.

@Davidfw1960: Interesting approach. I will give it a try.
At the end now I understand this chapter much better. Maybe an example here would have helped.

thanks at all, I’m happy now.

11

Thx, this helped me too!