List entries within an attribute are processed twice

[pedolsky]

The problem

I'm using several trigger based template sensors with a list within an attribute, based on examples like

here or here.

Since 2023.9, the list entries are duplicated.

What version of Home Assistant Core has the issue?

core-2023.9.1

What was the last working version of Home Assistant Core?

core.2023.8

What type of installation are you running?

Home Assistant Supervised

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

template:
  - trigger:
      - platform: state
        entity_id:
          - input_boolean.test
          - binary_sensor.bewegung_ankleide
          - binary_sensor.bewegung_flur
          - binary_sensor.bewegung_garderobe
          - binary_sensor.bewegung_hg06335
          - binary_sensor.bewegung_kuche
          - binary_sensor.bewegung_trinkbrunnen
          - binary_sensor.eingangstur
          - binary_sensor.kamera_loggia
          - binary_sensor.loggiatur
        from: 'off'
        to: 'on'
    sensor:
      - name: Recent
        state: "{{ now().timestamp() | timestamp_custom() }}"
        attributes:
          history: >
            {% set current = this.attributes.get('history', []) %}
            {% set new = [{
              "name": trigger.to_state.name,
              "time": now().isoformat() }] %}
            {{ (new + current)[:10] }}

### Anything in the logs that might be useful for us?

```txt
no

Additional information

No response

[home-assistant]

Hey there @PhracturedBlue, @tetienne, @home-assistant/core, mind taking a look at this issue as it has been labeled with an integration (template) you are listed as a code owner for? Thanks!

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[joel-bourquard]

Hi @pedolsky ,
Thanks for pinging me. I'm having the same issue - for reference: https://community.home-assistant.io/t/new-behavior-self-referencing-template-is-evaluated-twice/612296

Maybe this will help: adding a random() statement to the template confirms that the value is fully evaluated twice (with 2 different values of random).

[Mariusthvdb]

Sorry I didn't spot this is the community post. Checking the attributes now reveals the issue here too.

Notifications themselves are Not listed twice (that's what I figured to mention to be about at first ), attributes are:

Btw the Frontend has issues of its own ;-)

[tdejneka]

Until the bug is fixed, enhance the template to discard duplicates using the unique filter. In your example, duplicates are any list items with the same time value.

Change this:

{{ (new + current)[:10] }}

To this:

 {{ ((new + current) | unique(attribute='time') | list)[:10] }}

---

In Mariusthvdb's example, duplicates would be list items with the same created_at value.

[emufan]

Until the bug is fixed

This bug is not related in special to attributes, but that every trigger is now fired twice?

So this could be same reason as in my case, described in the forum:
https://community.home-assistant.io/t/template-sensor-adds-twice-as-much-correct-in-2023-9-1-compared-to-2023-8-x/612822/3

[emontnemery]

Fixed by #100119