Dynamic Service Calls

Oct 31, 2017 | Blog, Configuration, Home Assistant, JINJA

You’ve got a sweet automation but you need to grab some data from whatever triggered it. Luckily Home Assistant has the ability to use Jinja in automation via templates so you can get your information to another service. In my example, I’m using an automation where someone has arrived home so I use the TTS engine to welcome them home based on the name of the person who came home.

automation:
  - id: welcome_home
    alias: Welcome Home
    initial_state: True
    trigger:
      - platform: state
        entity_id: device_tracker.brian
        from: 'not_home'
        to: 'home'
        for:
          minutes: 2
      - platform: state
        entity_id: device_tracker.christina
        from: 'not_home'
        to: 'home'
        for:
          minutes: 2
    action:
      service: script.welcome_home
      data_template:
        user: '{{trigger.to_state.attributes.friendly_name}}'

You can also use templates to control which entities are passed to the service call; this example is an Alexa intent. You can see both the player and source keys are used to determine the entity and which source to use.

  MediaPlayerSourceIntent:
    action:
      service: media_player.select_source
      data_template:
        entity_id: 'media_player.{{player|replace(" ", "_")|lower}}'
        source: '{{source}}'
    speech:
      text: 'OK. Changing {{player}} to {{source}}'