Templating
This is an advanced feature of Home Assistant. You’ll need a basic understanding of the following things:
- Home Assistant architecture, especially states.
- State object
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:
- Formatting outgoing messages in, for example, the notify and alexa components.
- Process incoming data from sources that provide raw data, like MQTT, REST sensor, or the command line sensor.
- Automation Templating.
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
data_template:
message: >
{% if is_state('device_tracker.paulus', 'home') %}
Ha, Paulus is home!
{% else %}
Paulus is at {{ states('device_tracker.paulus') }}.
{% endif %}
Jinja2 supports a wide 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 forsensor.temperature
.states('device_tracker.paulus')
will return the state string (not the object) of the given entity orunknown
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.- For specific values:
now().second
,now().minute
,now().hour
,now().day
,now().month
,now().year
,now().weekday()
andnow().isoweekday()
- For specific values:
utcnow()
will be rendered as UTC time.- For specific values:
utcnow().second
,utcnow().minute
,utcnow().hour
,utcnow().day
,utcnow().month
,utcnow().year
,utcnow().weekday()
andutcnow().isoweekday()
.
- For specific values:
as_timestamp()
will convert datetime object or string to UNIX timestampdistance()
will measure the distance in meters between home, entity, coordinates.closest()
will find the closest entity.float
will format the output as float.strptime(string, format)
will parse a string to a datetime based on a format.log(value, base)
will take the logarithm of the input. When the base is omitted, it defaults toe
- the natural logarithm. Can also be used as a filter.- Filter
round(x)
will convert the input to a number and round it tox
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']
Rendering templates with time is dangerous as updates only trigger templates in sensors based on entity state changes.
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) }}
{{ value_json | log }}
{{ log(1000, 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 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]}}