cap:state - state tracking

The state-capability provides a way to get and update the state of a thing. State is split into several state keys that are updated separately.

if(thing.matches('cap:state')) {
  console.log('Current state:', this.state);
}

API

state()

Get the current overall state.

Returns:Promise that resolves to an object representing the current state. Keys represent names of the state key.

Usage:

const state = await thing.state();
console.log('State is', state);
console.log('Value of power is', state.power);

Events

stateChanged

State has changed for the thing.

thing.on('stateChanged', change =>
  console.log('Key', change.key, 'changed to', change.value)
);

Protected methods

getState(key[, defaultValue])

Get the current value of the given state key.

Arguments:

• power (string) – The state key to get value for.
• defaultValue – Fallback to return if the state key is not set.

Returns:

The value for the state key, the default value or null.

updateState(key, value)

Update the state of the given key. This will update the state key and emit the event stateChanged.

Arguments:

• key (string) – The state key to update.
• value – The new value of the state key.

Returns:

Boolean indicating if the state value has changed.

removeState(key)

Remove state stored for the given key. Will emit a stateChanged event.

Arguments:

• key (string) – The state key to remove.

Implementing capability

The state-capability has no functions that need to be implemented. updateState can be called at any time to update a state key.

const { Thing, State } = require('abstract-things');

class Example extends Thing.with(State) {
  constructor() {
    super();

    this.updateState('key', true);
  }
}