developers.home-assistant/docs/api/native-app-integration/sensors.md

title
Sensors

The mobile_app integration supports exposing custom sensors that can be managed entirely via your app.

Registering a sensor

All sensors must be registered before they can get updated. You can only register one sensor at a time, unlike updating sensors.

To register a sensor, make a request to the webhook like this:

{
  "data": {
    "attributes": {
      "foo": "bar"
    },
    "device_class": "battery",
    "icon": "mdi:battery",
    "name": "Battery State",
    "state": "12345",
    "type": "sensor",
    "unique_id": "battery_state",
    "unit_of_measurement": "%",
    "state_class": "measurement",
    "entity_category": "diagnostic",
    "disabled": true
  },
  "type": "register_sensor"
}

The valid keys are:

Key	Type	Required	Description
attributes	object	No	Attributes to attach to the sensor
device_class	string	No	One of the valid device classes. Binary Sensor Classes, Sensor Classes
icon	Material Design Icon (string)	No	Must be prefixed mdi:. If not provided, default value is mdi:cellphone
name	string	Yes	The name of the sensor
state	bool, float, int, string	Yes	The state of the sensor
type	string	Yes	The type of the sensor. Must be one of binary_sensor or sensor
unique_id	string	Yes	An identifier unique to this installation of your app. You'll need this later. Usually best when its a safe version of the sensor name
unit_of_measurement	string	No	The unit of measurement for the sensor
state_class	string	No	The state class of the entity (sensors only)
entity_category	string	No	The entity category of the entity
disabled	boolean	No	If the entity should be enabled or disabled.

Sensors will appear as soon as they are registered.

Updating a sensor

Once a sensor has been registered, you need to update it. This is very similar to registering it, but you can update all your sensors at the same time.

For example, to update the sensor we registered above, you would send this:

{
  "data": [
    {
      "attributes": {
        "hello": "world"
      },
      "icon": "mdi:battery",
      "state": 123,
      "type": "sensor",
      "unique_id": "battery_state"
    }
  ],
  "type": "update_sensor_states"
}

Only some of the keys are allowed during updates:

Key	Type	Required	Description
attributes	object	No	Attributes to attach to the sensor
icon	Material Design Icon (string)	No	Must be prefixed mdi:
state	bool, float, int, string	Yes	The state of the sensor
type	string	Yes	The type of the sensor. Must be one of binary_sensor or sensor
unique_id	string	Yes	An identifier unique to this installation of your app. You'll need this later. Usually best when its a safe version of the sensor name

The response to updating a sensor is a dictionary with unique_id => update result.

The key is_disabled will be added to successful updates if the entity is disabled inside Home Assistant. This means the app can disable sending updates to the sensor.

If an update was unsuccessful, an error is returned.

{
  "battery_state": {
    "success": true
  },
  "battery_level": {
    "success": true,
    "is_disabled": true
  },
  "battery_charging": {
    "success": false,
    "error": {
      "code": "not_registered",
      "message": "Entity is not registered",
    }
  },
  "battery_charging_state": {
    "success": false,
    "error": {
      "code": "invalid_format",
      "message": "Unexpected value for type",
    }
}

Keeping sensors in sync with Home Assistant

Users can enable and disable entities in Home Assistant. A disabled entity will not be added to Home Assistant, even if offered by the integration. This means that it won't make sense for phones to keep sending data to entities that are not enabled in Home Assistant.

When a sensor is enabled/disabled in the app, the app should send a register_sensor webhook for this sensor and set disabled to true or false.

When the mobile app sends an update_sensor_states webhook to update the data for an entity that is disabled, the update result will contain an is_disabled key with a value of true. This is an indicator that the mobile app needs to synchronize the enabled states from Home Assistant to the mobile app.

{
  "battery_level": {
    "success": true,
  },
  "battery_charging": {
    "success": true,
    "is_disabled": true
  }
}

When the user enables/disables an entity in Home Assistant, it needs to be synchronized to the mobile app. The get_config webhook response contains an entities key. This is a dictionary mapping unique_id to {"disabled": boolean}. The mobile app should adopt these enabled settings.

{
  // ...
  "entities": {
    "battery_level": {
      "disabled": false
    },
    "battery_charging": {
      "disabled": true
    },
  }
}