core/homeassistant/components/sensor/mqtt.py

81 lines
2.4 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 homeassistant.components.mqtt as mqtt
from homeassistant.const import CONF_VALUE_TEMPLATE, STATE_UNKNOWN
from homeassistant.helpers.entity import Entity
from homeassistant.helpers import template
_LOGGER = logging.getLogger(__name__)
DEFAULT_NAME = "MQTT Sensor"
DEFAULT_QOS = 0
DEPENDENCIES = ['mqtt']
# pylint: disable=unused-argument
def setup_platform(hass, config, add_devices_callback, discovery_info=None):
"""Setup MQTT Sensor."""
if config.get('state_topic') is None:
_LOGGER.error("Missing required variable: state_topic")
return False
add_devices_callback([MqttSensor(
hass,
config.get('name', DEFAULT_NAME),
config.get('state_topic'),
config.get('qos', DEFAULT_QOS),
config.get('unit_of_measurement'),
config.get(CONF_VALUE_TEMPLATE))])
# pylint: disable=too-many-arguments, too-many-instance-attributes
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
def message_received(topic, payload, qos):
"""A new MQTT message has been received."""
if value_template is not None:
payload = template.render_with_possible_json_value(
hass, value_template, payload)
self._state = payload
self.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