Trying to automate based on two datetime input helpers

Configuration
1

Hello,

I am trying to automate my shades so they would open on a set time partially and than after an offset period they would open completly.

I made a helper to set the initial time. This gives no problem. But its when I try to combine both helpers the initial time and the offset, I run into trouble.

I used the template editor to test the result and it gives me the correct hour (08:05:00) but the automation doesn’t accept it… I get Message malformed: Expected HH:MM, HH:MM:SS or Entity ID with domain ‘input_datetime’ or ‘sensor’ @ data[‘at’][0]

the YAML I am trying is the following

at: "{{ (state_attr('input_datetime.initial_time', 'timestamp') + state_attr('input_datetime.offset_time', 'timestamp')) | timestamp_custom('%H:%M:%S', False) }}"

Is it not possible what I am trying to do, or is there a an error in my template?

2

Why not two simple automations? One triggered by the set time and the other by the shades having been partially open for the offset period. Much easier to maintain.

3

Make a template sensor and use that as the at:. Currently, you cannot template the at: field.

template:
- sensor:
  - name: Shades Time
    unique_id: Shades Time
    device_class: timestamp
    state: >
      {{ states('input_datetime.initial_time') | today_at + states('input_datetime.offset_time') | as_timedelta }}

then

trigger:
- platform: time
  at: sensor.shades_time