Template

The template integration allows creating entities which derive their values from other entities. This is done by defining templates for each property of an entity, like the name or the state. Entities are updated automatically whenever a value that a template relies on changes.

For template sensors it’s also possible to derive the state from automation triggers.

Available template platforms:

• Alarm_control_panel
• Binary_sensor
• Cover
• Fan
• Light
• Lock
• Sensor (this page)
• Switch
• Vacuum
• Weather

Configuration

The configuration of Template Sensors depends on what you want them to be. Adding the following to your configuration.yaml file will create two sensors, one for the current sun angle and one for the time of the next sunrise:

# Example configuration.yaml entry
sensor:
  - platform: template
    sensors:
      solar_angle:
        friendly_name: "Sun angle"
        unit_of_measurement: "degrees"
        value_template: "{{ state_attr('sun.sun', 'elevation') }}"

      sunrise:
        value_template: "{{ state_attr('sun.sun', 'next_rising') }}"

Configuration for trigger-based template sensors

Trigger-based template sensors allow the user to define an automation trigger for a group of template sensors. Whenever the trigger fires, the template sensor will re-render and it will have access to the trigger data in the templates. This feature is a great way to create data based on webhook data, or have sensors be updated based on a time-schedule.

Trigger-based template entities are defined in YAML directly under the template: key. You can define multiple configuration blocks as a list. Each block defines one or more triggers and the sensors that should be updated when the trigger fires.

Trigger-based entities do not automatically update when states referenced in the templates change. This functionality can be added by defining a state trigger for each entity that you want to trigger updates.

# Example configuration entry
template:
  - trigger:
      - platform: webhook
        webhook_id: my-super-secret-webhook-id
    sensor:
      - name: "Webhook Temperature"
        state: "{{ trigger.json.temperature }}"
      - name: "Webhook Humidity"
        state: "{{ trigger.json.humidity }}"

You can test this trigger entity with the following CURL command:

curl --header "Content-Type: application/json" \
  --request POST \
  --data '{"temperature": 5, "humidity": 34}' \
  http://homeassistant.local:8123/api/webhook/my-super-secret-webhook-id

Configuration under the template: key uses a different format compared to the platform configuration.

It's currently only possible to define trigger-based entities via the top-level configuration. These entities are not yet included when reloading template entities.

Considerations

Startup

If you are using the state of a platform that takes extra time to load, the Template Sensor may get an unknown state during startup. To avoid this (and the resulting error messages in your log file), you can use is_state() function in your template. For example, you would replace {{ states.cover.source.state == 'open' }} with this equivalent that returns true/false and never gives an unknown result:

{{ is_state('switch.source', 'on') }}

Sensor state updates

The template engine works out what entities are used to trigger an update of the sensor and recalculates the result when one of those entities change.

If you use a template that depends on the current time or some other non-deterministic result not sourced from entities, create an interval-based automation that calls the service homeassistant.update_entity for the sensor requiring updates. See the example below.

Unique ID

The optional unique_id can be set so the entity will be registered in the entity registry. This allows changing the name, icon and entity_id from the web interface instead of having to use the customize key in your configuration.yaml file.

Examples

In this section, you find some real-life examples of how to use this sensor.

Sun Angle

This example shows the sun angle in the frontend.

sensor:
  - platform: template
    sensors:
      solar_angle:
        friendly_name: "Sun Angle"
        unit_of_measurement: "°"
        value_template: "{{ '%+.1f'|format(state_attr('sun.sun', 'elevation')) }}"

Renaming Sensor Output

If you don’t like the wording of a sensor output, then the Template Sensor can help too. Let’s rename the output of the Sun component as a simple example:

sensor:
  - platform: template
    sensors:
      sun_state:
        friendly_name: "Sun State"
        value_template: >-
          {% if is_state('sun.sun', 'above_horizon') %}
            up
          {% else %}
            down
          {% endif %}

Multiline Example With an if Test

This example shows a multiple line template with an if test. It looks at a sensing switch and shows on/off in the frontend.

sensor:
  - platform: template
    sensors:
      kettle:
        friendly_name: "Kettle"
        value_template: >-
          {% if is_state('switch.kettle', 'off') %}
            off
          {% elif state_attr('switch.kettle', 'kwh')|float < 1000 %}
            standby
          {% elif is_state('switch.kettle', 'on') %}
            on
          {% else %}
            failed
          {% endif %}

Change The Unit of Measurement

With a Template Sensor, it’s easy to convert given values into others if the unit of measurement doesn’t fit your needs.

sensor:
  - platform: template
    sensors:
      transmission_down_speed_kbps:
        friendly_name: "Transmission Down Speed"
        unit_of_measurement: "kB/s"
        value_template: "{{ states('sensor.transmission_down_speed')|float * 1024 }}"

      transmission_up_speed_kbps:
        friendly_name: "Transmission Up Speed"
        unit_of_measurement: "kB/s"
        value_template: "{{ states('sensor.transmission_up_speed')|float * 1024 }}"

Change The Icon

This example shows how to change the icon based on the day/night cycle.

sensor:
  - platform: template
    sensors:
      day_night:
        friendly_name: "Day/Night"
        value_template: >-
          {% if is_state('sun.sun', 'above_horizon') %}
            Day
          {% else %}
            Night
          {% endif %}
        icon_template: >-
          {% if is_state('sun.sun', 'above_horizon') %}
            mdi:weather-sunny
          {% else %}
            mdi:weather-night
          {% endif %}

Change The Entity Picture

This example shows how to change the entity picture based on the day/night cycle.

sensor:
  - platform: template
    sensors:
      day_night:
        friendly_name: "Day/Night"
        value_template: >-
          {% if is_state('sun.sun', 'above_horizon') %}
            Day
          {% else %}
            Night
          {% endif %}
        entity_picture_template: >-
          {% if is_state('sun.sun', 'above_horizon') %}
            /local/daytime.png
          {% else %}
            /local/nighttime.png
          {% endif %}

Change the Friendly Name Used in the Frontend

This example shows how to change the friendly_name based on a state.

sensor:
  - platform: template
    sensors:
      net_power:
        friendly_name_template: >-
          {% if states('sensor.power_consumption')|float < 0 %}
            Power Consumption
          {% else %}
            Power Production
          {% endif %}
        value_template: "{{ states('sensor.power_consumption') }}"
        unit_of_measurement: "kW"

Add Custom Attributes

This example shows how to add custom attributes.

sensor:
  - platform: template
    sensors:
      my_device:
        value_template: >-
          {% if is_state('device_tracker.my_device_nmap','home') %}
            Home
          {% else %}
            {{ states('device_tracker.my_device_gps') }}
          {% endif %}
        attribute_templates:
          latitude: >-
            {% if is_state('device_tracker.my_device_nmap','home') %}
              {{ state_attr('zone.home','latitude') }}
            {% else %}
              {{ state_attr('device_tracker.my_device_gps','latitude') }}
            {% endif %}
          longitude: >-
            {% if is_state('device_tracker.my_device_nmap','home') %}
              {{ state_attr('zone.home','longitude') }}
            {% else %}
              {{ state_attr('device_tracker.my_device_gps','longitude') }}
            {% endif %}

Working without entities

The template sensors are not limited to use attributes from other entities but can also work with Home Assistant’s template extensions.

This template contains no entities that will trigger an update but the now() will cause it to update every minute:

sensor:
  - platform: time_date
    display_options:
      - 'date'
  - platform: template
    sensors:
      nonsmoker:
        value_template: '{{ ( ( as_timestamp(now()) - as_timestamp(strptime("06.07.2018", "%d.%m.%Y")) ) / 86400 ) | round(2) }}'
        friendly_name: "Not smoking"
        unit_of_measurement: "Days"

Updating templates using random

If you use the random filter, you may want the template to select a different random element every now and then. If the template does not update automatically due to entity changes it can be updated periodically by using the homeassistant.update_entity service with a time pattern automation. For example, this will render a new random number every five minutes:

sensor:
  - platform: template
    sensors:
      random_number:
        friendly_name: "Random number"
        value_template: "{{ range(0,100)|random }}"

automation:
  - alias: "Update random number template"
    trigger:
      - platform: time_pattern
        minutes: "/5"
    action:
      - service: homeassistant.update_entity
        target:
          entity_id: sensor.random_number