Check if entity has a value: has_value

The has_value template function checks whether an entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more] exists and has a meaningful state. It returns false if the entity doesn’t exist, is unavailable, or is unknown. Otherwise it returns true.

This is essential for building robust templatesA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] that don’t break when a sensorSensors return information about a thing, for instance the level of water in a tank. [Learn more] goes offline or hasn’t reported yet. Sensors can temporarily become unavailable (for example, when a battery-powered deviceA device is a model representing a physical or logical unit that contains entities. goes to sleep) or unknown (during Home Assistant startup). By checking with has_value first, you can avoid errors in calculations or show a fallback message instead of displaying confusing values.

Usage

Here’s how to use this template function. Copy any example and adjust it to your setup.

{{ has_value("sensor.temperature") }}

true

{{ "sensor.temperature" | has_value }}

true

{% if "sensor.temperature" is has_value %}
  Sensor is available
{% endif %}

Sensor is available

Function signature

The signature is a technical summary of this template function. It shows the name of the function, the values (called parameters) it accepts, and what type of data each parameter expects (for example, a piece of text or a number).

Function parameters that have a = with a value after them are optional. If you leave them out, the default value shown is used automatically.

Function parameters without a = are usually required. A few optional parameters have no default value, so the signature shows them without a = as well. To check whether a parameter is required, look at the parameter list below the signature. Each parameter is marked as Required or Optional.

The most common optional parameter without a default value is default. The default parameter sets the value a function returns when the function can’t produce a result, for example, when float gets text that isn’t a number. If you leave out default, there is no fallback value, so most functions raise an error and the template fails. The parameter list of each function says what happens. If you set default, the function returns your value instead.

round(
    value: Any,
    precision: int = 0,
    method: str = "common",
    default: Any,
) -> float | int | Any

has_value(
    entity_id: str,
) -> bool

Function parameters

The following parameters can be provided to this function.

Good to know

• Returns false for missing entities, so use this before reading a state with states to avoid chasing unknown or unavailable downstream.
• Treats both unavailable and unknown the same. If you only want to exclude one, compare to the specific state with is_state.

Try it yourself

Ready to test this? Open Settings > Tools > Template, paste the example into the Template editor, and watch the result update on the right. Edit the values to see how the function adapts to your own entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more].

More examples

Real scenarios where this function comes up in automations and templates. Copy any example and adapt it to your setup.

Safely read a sensor value with a fallback

Only use the sensor value if it’s available, otherwise show a default message.

{% if has_value("sensor.outdoor_temperature") %}
  It's {{ states("sensor.outdoor_temperature") }}°C outside
{% else %}
  Temperature sensor is not available
{% endif %}

It's 18.5°C outside

Guard a calculation

Prevent errors by checking that a sensor has a value before doing math with it.

{% if has_value("sensor.power_usage") %}
  {{ states("sensor.power_usage") | float * 0.25 }}
{% else %}
  0
{% endif %}

62.5

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with your template and expected result, or share on our subreddit /r/homeassistant.

Related template functions

These functions work well alongside this one:

• Get entity state: states - Returns the state value of an entity, or lets you iterate over all entity states.

• Test entity state: is_state - Tests if an entity is in a specific state.

• Get state attribute: state_attr - Returns the value of a specific attribute from an entity’s state.