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Templating

This is an advanced feature of Home Assistant. You’ll need a basic understanding of the following things:

Templating is a powerful feature in Home Assistant that allows the user control over information that is going into and out of the system. It is used for:

Building templates

Templating in Home Assistant is powered by the Jinja2 templating engine. This means that we are using their syntax and make some custom Home Assistant variables available to templates during rendering. We will not go over the basics of the syntax, as Jinja2 does a lot better job at this in their Jinja2 documentation.

The frontend has a template editor developer tool to help develop and debug templates.

Templates can get big pretty fast. To keep a clear overview, consider using YAML multiline strings to define your templates:

script:
  msg_who_is_home:
    sequence:
      - service: notify.notify
        message: >
          {% if is_state('device_tracker.paulus', 'home') %}
            Ha, Paulus is home!
          {% else %}
            Paulus is at {{ states('device_tracker.paulus') }}.
          {% endif %}

Jinja2 supports a width variety of operations:

Home Assistant template extensions

Home Assistant adds extensions to allow templates to access all of the current states:

  • Iterating states will yield each state sorted alphabetically by entity ID.
  • Iterating states.domain will yield each state of that domain sorted alphabetically by entity ID.
  • states.sensor.temperature returns the state object for sensor.temperature.
  • states('device_tracker.paulus') will return the state string (not the object) of the given entity or unknown if it doesn’t exist.
  • is_state('device_tracker.paulus', 'home') will test if the given entity is specified state.
  • is_state_attr('device_tracker.paulus', 'battery', 40) will test if the given entity is specified state.
  • now() will be rendered as current time in your time zone.
  • utcnow() will be rendered as UTC time.
  • as_timestamp() will convert datetime object or string to UNIX timestamp
  • distance() will measure the distance in meters between home, entity, coordinates.
  • closest() will find the closest entity.
  • relative_time(timestamp) will format the date time as relative time vs now (ie 7 seconds)
  • float will format the output as float.
  • strptime(string, format) will parse a string to a datetime based on a format.
  • Filter round(x) will convert the input to a number and round it to x decimals.
  • Filter timestamp_local will convert an UNIX timestamp to local time/data.
  • Filter timestamp_utc will convert an UNIX timestamp to UTC time/data.
  • Filter timestamp_custom(format_string, local_boolean) will convert an UNIX timestamp to a custom format, the use of a local timestamp is default, supporting Python format options.
  • Filter max will obtain the larget item in a sequence.
  • Filter min will obtain the smallest item in a sequence.

If your template uses an entity_id that begins with a number (example: states.device_tracker.2008_gmc) you must use a bracket syntax to avoid errors caused by rendering the entity_id improperly. In the example given, the correct syntax for the device tracker would be: states.device_tracker['2008_gmc']

Home Assistant template extensions

In templates, besides the normal state object methods and properties, there are also some extra things available:

  • states.sensor.temperature.state_with_unit will print the state of the entity and, if available, the unit.

Examples

States

The next two statements result in same value if state exists. The second one will result in an error if state does not exist.

{{ states('device_tracker.paulus') }}
{{ states.device_tracker.paulus.state }}

Attributes

Print an attribute if state is defined

{% if states.device_tracker.paulus %}
  {{ states.device_tracker.paulus.attributes.battery }}
{% else %}
  ??
{% endif %}

Sensor states

Print out a list of all the sensor states.

{% for state in states.sensor %}
  {{ state.entity_id }}={{ state.state }},
{% endfor %}

{% if is_state('device_tracker.paulus', 'home') %}
  Ha, Paulus is home!
{% else %}
  Paulus is at {{ states('device_tracker.paulus') }}.
{% endif %}

{{ states.sensor.temperature | float + 1 }}

{{ (states.sensor.temperature | float * 10) | round(2) }}

{% if states('sensor.temperature') | float > 20 %}
  It is warm!
{%endif %}

{{ as_timestamp(states.binary_sensor.garage_door.last_changed) }}

{{ as_timestamp(now()) - as_timestamp(states.binary_sensor.garage_door.last_changed) }}

Distance examples

If only 1 location is passed in, Home Assistant will measure the distance from home.

Using Lat Lng coordinates: {{ distance(123.45, 123.45) }}

Using State: {{ distance(states.device_tracker.paulus) }}

These can also be combined in any combination:
{{ distance(123.45, 123.45, 'device_tracker.paulus') }}
{{ distance('device_tracker.anne_therese', 'device_tracker.paulus') }}

Closest examples

Find entities closest to the Home Assistant location:

Query all entities: {{ closest(states) }}
Query all entities of a specific domain: {{ closest('states.device_tracker') }}
Query all entities in group.children: {{ closest('group.children') }}
Query all entities in group.children: {{ closest(states.group.children) }}

Find entities closest to a coordinate or another entity. All previous arguments still apply for 2nd argument.

Closest to a coordinate: {{ closest(23.456, 23.456, 'group.children') }}
Closest to an entity: {{ closest('zone.school', 'group.children') }}
Closest to an entity: {{ closest(states.zone.school, 'group.children') }}

Combined

Since closest returns a state, we can combine it with distance too.

{{ closest(states).name }} is {{ distance(closest(states)) }} meters away.

Processing incoming data

The other part of templating is processing incoming data. It will allow you to modify incoming data and extract only the data you care about. This will work only for platforms and components that mentioned support for this in their documentation.

It depends per component or platform, but it is common to be able to define a template using the value_template configuration key. When a new value arrives, your template will be rendered while having access to the following values on top of the usual Home Assistant extensions:

Variable Description
value The incoming value.
value_json The incoming value parsed as JSON.

This means that if the incoming values looks like the sample below:

{
  "on": "true",
  "temp": 21
}

The template for on would be:

'{{value_json.on}}'

Nested JSON in a response is supported as well

{
  "sensor": {
    "type": "air",
    "id": "12345"
  },
  "values": {
    "temp": 26.09,
    "hum": 56.73,
  }
}

Just use the “Square bracket notation” to get the value.

'{{ value_json["values"]["temp"] }}'

The following overview contains a couple of options to get the needed values:

# Incoming value:
{"primes": [2, 3, 5, 7, 11, 13]}

# Extract third prime number
{{ value_json.primes[2] }}

# Format output
{{ "%+.1f" | value_json }}

# Math
{{ value_json | float * 1024 }}
{{ float(value_json) * (2**10) }}

# Timestamps
{{ value_json.tst | timestamp_local }}
{{ value_json.tst | timestamp_utc }}
{{ value_json.tst | timestamp_custom('%Y' True) }}

To evaluate a response, go to the template developer tool icon template developer tools, create your output into “Template”, and check the result.


{% set value_json=
    {"name":"Outside",
	 "device":"weather-ha",
     "data":
	    {"temp":"24C",
		 "hum":"35%"
		 }	}%}

{{value_json.data.hum[:-1]}}