core/homeassistant/components/sensor/mqtt.py

89 lines
2.6 KiB
Python

"""
Support for MQTT sensors.
For more details about this platform, please refer to the documentation at
https://home-assistant.io/components/sensor.mqtt/
"""
import logging
import voluptuous as vol
from homeassistant.core import callback
from homeassistant.components.mqtt import CONF_STATE_TOPIC, CONF_QOS
from homeassistant.const import (
CONF_NAME, CONF_VALUE_TEMPLATE, STATE_UNKNOWN, CONF_UNIT_OF_MEASUREMENT)
from homeassistant.helpers.entity import Entity
import homeassistant.components.mqtt as mqtt
import homeassistant.helpers.config_validation as cv
_LOGGER = logging.getLogger(__name__)
DEFAULT_NAME = 'MQTT Sensor'
DEPENDENCIES = ['mqtt']
PLATFORM_SCHEMA = mqtt.MQTT_RO_PLATFORM_SCHEMA.extend({
vol.Optional(CONF_NAME, default=DEFAULT_NAME): cv.string,
vol.Optional(CONF_UNIT_OF_MEASUREMENT): cv.string,
})
# pylint: disable=unused-argument
def setup_platform(hass, config, add_devices, discovery_info=None):
"""Setup MQTT Sensor."""
value_template = config.get(CONF_VALUE_TEMPLATE)
if value_template is not None:
value_template.hass = hass
add_devices([MqttSensor(
hass,
config.get(CONF_NAME),
config.get(CONF_STATE_TOPIC),
config.get(CONF_QOS),
config.get(CONF_UNIT_OF_MEASUREMENT),
value_template,
)])
class MqttSensor(Entity):
"""Representation of a sensor that can be updated using MQTT."""
def __init__(self, hass, name, state_topic, qos, unit_of_measurement,
value_template):
"""Initialize the sensor."""
self._state = STATE_UNKNOWN
self._hass = hass
self._name = name
self._state_topic = state_topic
self._qos = qos
self._unit_of_measurement = unit_of_measurement
@callback
def message_received(topic, payload, qos):
"""A new MQTT message has been received."""
if value_template is not None:
payload = value_template.async_render_with_possible_json_value(
payload, self._state)
self._state = payload
hass.async_add_job(self.async_update_ha_state())
mqtt.subscribe(hass, self._state_topic, message_received, self._qos)
@property
def should_poll(self):
"""No polling needed."""
return False
@property
def name(self):
"""Return the name of the sensor."""
return self._name
@property
def unit_of_measurement(self):
"""Return the unit this state is expressed in."""
return self._unit_of_measurement
@property
def state(self):
"""Return the state of the entity."""
return self._state