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States

Entity proxies provide a variety of tools for interacting with state, always having logic updated to reflect current point in time.

state​

The type definition for state provided to any particular entity is set up to reflect the value in Home Assistant. Some domains, like binary_sensor, may feature string unions instead of simple primitives.

import { TServiceparams } from "@digital-alchemy/core";

export function EntityStates({ hass, lifecycle, logger }: TServiceParams) {
  const mySensor = hass.refBy.id("sensor.outdoor_temperature");
  lifecycle.onReady(() => {
    logger.info("current outdoor temperature is %s", mySensor.state);
  });

  mySensor.onUpdate(new_state => {
    // new_state.state === mySensor.state
    // both are valid and refer to the same thing
    logger.info("current outdoor temperature is now %s", mySensor.state);
  });
}

assignments​

Assignments to the state property are possible, with a special call being made to attempt to set the state.

This relies on some quirks within Home Assistant to work right, and may not always do what you think it should. You should seek to use proper service calls to set state when possible.

attributes​

Like state, the entity attributes are always available on demand (and do have assignment support).

logger.info("friendly_name = %s", mySensor.attributes.friendly_name);

previous​

The previous property provides a simple path to accessing the immediate previous state / attributes of the entity from any workflow.

mySensor.onUpdate((new_state, old_state) => {
  // Both of these are equivalent
  // old_state.state === mySensor.previous.state
});

history​

If you need more than just the current / previous state, entities expose a history querying function Access historical state changes for an entity:

const now = dayjs();
const from = now.substract(1, "day");

// Get history for the last 24 hours
const history = await mySensor.history(from, now);

last_changed / last_*​

Entities also expose a few readonly timestamps for tracking:

  • last_changed
  • last_reported
  • last_updated