Performing date math in template helper

Configuration
1

I’m having an issue using a template helper and adding a year to a date.

Background - I have a Kohler generator with the OnQue system, and I’m using the OnQue integration to read the data. When I do generator maintenance, the OnQue integration does not return the date or hours when the maintenance was performed. So I’ve added two helpers which I will manually update when the maintenance is performed:

  1. input_datetime.generator_maintenance_performed_date which is a date/time helper.
  2. input_number.generator_maintenance_performed_hours which is a number helper.

On a dashboard, I want to show the hours or date that the maintenance is due (every 150 hours or yearly). I’ve created template helpers for each of these. I have the hours one working, but I can’t get the date one to return the next year.

In developer tools | Templates, I created this template which works properly:

{% set datetime = as_datetime(states('input_datetime.generator_maintenance_performed_date')) %}
{{datetime.replace(year=datetime.year+1)|as_datetime}}

However, in the helper that I’ve created, it is always returning “Unknown”.

HA Helper Template Date Math issue
HA Helper Template Date Math issue866×1109 63.1 KB

Can anyone help me get this helper working properly?
Thanks!

2

That last datetime is superfluous, but shouldn’t have prevented the template from resolving. Try this anyway:

{% set datetime = as_datetime(states('input_datetime.generator_maintenance_performed_date')) %}
{{datetime.replace(year=datetime.year+1)}}
3

I get the same result (works in Dev Tools | Template, but not in the helper). Note that I was initially doing this, and tried adding that just in case it helped.

4

Try this version (works on my system in a Template Sensor helper).

{{ (states('input_datetime.generator_maintenance_performed_date') | as_datetime + timedelta(days=365)).date() }}
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5

Okay, this works (well, except for when adding the 365 days would include a Feb 29th, but this is close enough for me).

Thanks Taras!

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