Automation Templating

In Home Assistant 0.19 we introduced a new powerful feature: variables in scripts and automations. This makes it possible to adjust your condition and action based on the information of the trigger.

The trigger data made is available during template rendering as the trigger variable.

# Example configuration.yaml entries
automation:
  trigger:
    platform: state
    entity_id: device_tracker.paulus
  action:
    service: notify.notify
    data_template:
      message: >
        Paulus just changed from {{ trigger.from_state.state }}
        to {{ trigger.to_state.state }}

automation 2:
  trigger:
    platform: mqtt
    topic: /notify/+
  action:
    service_template: >
      notify.{{ trigger.topic.split('/')[-1] }}
    data_template:
      message: '{{ trigger.payload }}'

Important Template Rules

There are a few very important rules to remember when writing automation templates:

1. You must use data_template in place of data when using templates in the data section of a service call.
2. You must use service_template in place of service when using templates in the service section of a service call.
3. You must surround single-line templates with double quotes (") or single quotes (').
4. It is advised that you prepare for undefined variables by using if ... is not none or the default filter, or both.
5. It is advised that when comparing numbers, you convert the number(s) to a float or an int by using the respective filter.
6. While the float and int filters do allow a default fallback value if the conversion is unsuccessful, they do not provide the ability to catch undefined variables.

Remembering these simple rules will help save you from many headaches and endless hours of frustration when using automation templates.

Trigger State Object

Knowing how to access the state object of a trigger entity could be one of the more common questions. Here are a few ways for the state, numeric_state and template triggers:

• trigger.from_state will return the previous state object of the entity.
• trigger.to_state will return the new state object that triggered trigger.
• states[trigger.to_state.domain][trigger.to_state.object_id] will return the current state object of the entity.

Available Trigger Data

The following tables show the available trigger data per platform.

event

mqtt

numeric_state

state

sun

template

time

zone