core/homeassistant/components/sensor/arest.py

151 lines
4.0 KiB
Python

"""
homeassistant.components.sensor.arest
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The arest sensor will consume an exposed aREST API of a device.
Configuration:
To use the arest sensor you will need to add something like the following
to your configuration.yaml file.
sensor:
platform: arest
resource: http://IP_ADDRESS
monitored_variables:
- name: temperature
unit: '°C'
- name: humidity
unit: '%'
Variables:
resource:
*Required
IP address of the device that is exposing an aREST API.
These are the variables for the monitored_variables array:
name
*Required
The name of the variable you wish to monitor.
unit
*Optional
Defines the units of measurement of the sensor, if any.
Details for the API: http://arest.io
Format of a default JSON response by aREST:
{
"variables":{
"temperature":21,
"humidity":89
},
"id":"device008",
"name":"Bedroom",
"connected":true
}
"""
import logging
from requests import get, exceptions
from datetime import timedelta
from homeassistant.util import Throttle
from homeassistant.helpers.entity import Entity
_LOGGER = logging.getLogger(__name__)
# Return cached results if last scan was less then this time ago
MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=60)
def setup_platform(hass, config, add_devices, discovery_info=None):
""" Get the aREST sensor. """
resource = config.get('resource', None)
try:
response = get(resource, timeout=10)
except exceptions.MissingSchema:
_LOGGER.error("Missing resource or schema in configuration. "
"Add http:// to your URL.")
return False
except exceptions.ConnectionError:
_LOGGER.error("No route to device. "
"Please check the IP address in the configuration file.")
return False
rest = ArestData(resource)
dev = []
for variable in config['monitored_variables']:
if 'unit' not in variable:
variable['unit'] = ' '
if variable['name'] not in response.json()['variables']:
_LOGGER.error('Variable: "%s" does not exist', variable['name'])
else:
dev.append(ArestSensor(rest,
response.json()['name'],
variable['name'],
variable['unit']))
add_devices(dev)
class ArestSensor(Entity):
""" Implements an aREST sensor. """
def __init__(self, rest, location, variable, unit_of_measurement):
self.rest = rest
self._name = '{} {}'.format(location.title(), variable.title())
self._variable = variable
self._state = 'n/a'
self._unit_of_measurement = unit_of_measurement
self.update()
@property
def name(self):
""" The name of the sensor. """
return self._name
@property
def unit_of_measurement(self):
""" Unit the value is expressed in. """
return self._unit_of_measurement
@property
def state(self):
""" Returns the state of the device. """
return self._state
def update(self):
""" Gets the latest data from aREST API and updates the state. """
self.rest.update()
values = self.rest.data
if 'error' in values:
self._state = values['error']
else:
self._state = values[self._variable]
# pylint: disable=too-few-public-methods
class ArestData(object):
""" Class for handling the data retrieval. """
def __init__(self, resource):
self.resource = resource
self.data = dict()
@Throttle(MIN_TIME_BETWEEN_UPDATES)
def update(self):
""" Gets the latest data from aREST device. """
try:
response = get(self.resource, timeout=10)
if 'error' in self.data:
del self.data['error']
self.data = response.json()['variables']
except exceptions.ConnectionError:
_LOGGER.error("No route to device. Is device offline?")
self.data['error'] = 'n/a'