Using Templates within Automation triggers

I’m only a week or two into using HA and love it.

I’ve been struggling to access the “sensor_state” data of a Wemo Maker within an Automation trigger.

I’m already successfully using a template to get to the sensor_state within a Condition in one automation, but can’t get to the sensor_state within a trigger of another automation.

Here’s the one that works. It will only open the garage if the sensor says it’s currently closed (sensor - off);

- alias: Open Garage
    platform: event
    event_type: garage_open
    condition: template
    value_template: '{{ states.switch.garage_door.attributes.sensor_state == "off" }}'
    service: switch.turn_on
    entity_id: switch.garage_door

Here’s the one that doesn’t. I want to know when the garage opens (sensor on) and turn on a light for 5min;

- alias: Porch Light
    platform: template
    value_template: '{% if ("states.switch.garage_door.attributes.sensor_state", "on") %}true{% endif %}'
  condition: use_trigger_values
    condition: time
    after: '19:15:00'
    before: '6:00:00'
    - service: light.turn_on
      entity_id: light.front_door
    - delay: 0:05
    - service: light.turn_off
      entity_id: light.front_door

Any thoughts?


First off you should really only ever use a template trigger if there is no other way around it. Because this template will get rendered for EVERY state change of EVERY entity_id. So if another state changes while the sensor state of your sensor (switch.garage_door.attributes.sensor_state) is still on it will fire multiple times.

Furthermore why does your switch have an attribute called sensor state? Shouldn’t that be a sensor on his own?

But to your problem:
You could also try is_state_attr like in my multiline example.
I have had multiple instance where it was only possible to get templates to work by using multiline…in your case this would look like this:

value_template: >-
  {%- if is_state_attr("switch.garage_door", "sensor_state", "on") -%}
  {%- endif -%}

Thanks for your response.

For some reason, when the wemo maker is scanned by HA on startup, it’s relay switch appears as a switch, and the the sensor interface (a part of the wemo maker) appears as an attribute of the switch. I don’t know if it’s possible to manually configure it to be a seperate sensor within HA though…

I’ve input your code and that has done the trick. Now to make the conditions work…


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Well you could make a template sensor to at least ease the access of this value like described over here:

If you are planning on using the sensor in multiple automations it might make for an easier overview of your config.


I’ll give it a go.


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And if everything has been tested to work correctly with a newly created template sensor, you can decide too hide that template sensor (if wanted) by using the customization options to set hidden: true for the entity_id of the template sensor. Same for the physical sensor if needed.

Otherwise your dash will get cluttered with all these kind of (virtual) devices.

Is it possible to have a trigger based on an attribute change, rather than a state? Something like:

     platform: state
     entity_id: switch.garage_door.attributes.sensor_state

You could achieve a behaviour which reflects this with a template trigger. If you need further help with that let me know I’ll give you an example.


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Thanks. I figured it out. For reference for anyone finding this later, an example to get started is here:

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This is an old thread but it’s been passed around the chat a lot lately.
It’s referenced to not use a template trigger unless absolutely forced too - So I’m wondering about specifics. We can minimize quite a lot of our automation by being able to render the trigger dynamically, so I don’t fully understand why we wouldn’t.

It’s even mentioned in automation-trigger entirely.
Use Case:
Why not trigger a lights ‘off’ functionality if it’s on. Why make a lights on, and a light off automation - Assuming they both do the exact same thing.

Using MQTT to ‘remember’ which input source something was at. I’d want it to trigger every time an attribute of that entity changed, which I can’t find any way to do without a dynamic template.

Would love to see specifics as to why templating is bad, or how bad it is to know how much I should be avoiding it.


@jjpeet I’m also trying to use my Wemo Maker Sensor as a trigger to an action. What did you end up doing in the end? Might you share you experience.

I just solved what I’ve done here. Might be useful for anyone else.

Firstly: I create a template sensor to track the sensor on the wemo maker

  - platform: template
        value_template: '{{ states.switch.front_gates.attributes.sensor_state }}'
        friendly_name: 'Front Gate Magnetic Reed'
        entity_id: switch.front_gates

Second: I built my automation based on the template sensor changing state. As you can see I’m turning my LIFX light to RED when my front gate is open and then turning it off when the Gate is closed.

automation 1:
  alias: Turn LIFX to RED when Front Gate is Open
    platform: state
    entity_id: sensor.front_gate_reed
    state: 'off'
    service: light.turn_on
    entity_id: light.courtyard
      color_name: red
      brightness: 255

automation 2:
  alias: Turn LIFX off when Front Gate is Closed
    platform: state
    entity_id: sensor.front_gate_reed
    state: 'on'
    service: light.turn_off
    entity_id: light.courtyard
      transition: 3
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