Merge pull request #360 from fabaff/rest-sensor

Rest sensor

.coveragerc

@@ -70,6 +70,7 @@ omit =
     homeassistant/components/sensor/glances.py
     homeassistant/components/sensor/mysensors.py
     homeassistant/components/sensor/openweathermap.py
+    homeassistant/components/sensor/rest.py
     homeassistant/components/sensor/rfxtrx.py
     homeassistant/components/sensor/rpi_gpio.py
     homeassistant/components/sensor/sabnzbd.py

homeassistant/components/sensor/rest.py

@@ -0,0 +1,182 @@
+"""
+homeassistant.components.sensor.rest
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The rest sensor will consume JSON responses sent by an exposed REST API.
+
+For more details about this platform, please refer to the documentation at
+https://home-assistant.io/components/sensor.rest.html
+"""
+import logging
+import requests
+from json import loads
+from datetime import timedelta
+
+from homeassistant.util import Throttle
+from homeassistant.helpers.entity import Entity
+
+_LOGGER = logging.getLogger(__name__)
+
+DEFAULT_NAME = 'REST Sensor'
+DEFAULT_METHOD = 'GET'
+
+# Return cached results if last scan was less then this time ago
+MIN_TIME_BETWEEN_UPDATES = timedelta(seconds=60)
+
+
+# pylint: disable=unused-variable
+def setup_platform(hass, config, add_devices, discovery_info=None):
+    """ Get the REST sensor. """
+
+    use_get = False
+    use_post = False
+
+    resource = config.get('resource', None)
+    method = config.get('method', DEFAULT_METHOD)
+    payload = config.get('payload', None)
+
+    if method == 'GET':
+        use_get = True
+    elif method == 'POST':
+        use_post = True
+
+    try:
+        if use_get:
+            response = requests.get(resource, timeout=10)
+        elif use_post:
+            response = requests.post(resource, data=payload, timeout=10)
+        if not response.ok:
+            _LOGGER.error('Response status is "%s"', response.status_code)
+            return False
+    except requests.exceptions.MissingSchema:
+        _LOGGER.error('Missing resource or schema in configuration. '
+                      'Add http:// to your URL.')
+        return False
+    except requests.exceptions.ConnectionError:
+        _LOGGER.error('No route to resource/endpoint. '
+                      'Please check the URL in the configuration file.')
+        return False
+
+    try:
+        data = loads(response.text)
+    except ValueError:
+        _LOGGER.error('No valid JSON in the response in: %s', data)
+        return False
+
+    try:
+        data[config.get('variable')]
+    except KeyError:
+        _LOGGER.error('Variable "%s" not found in response: "%s"',
+                      config.get('variable'), data)
+        return False
+
+    if use_get:
+        rest = RestDataGet(resource)
+    elif use_post:
+        rest = RestDataPost(resource, payload)
+
+    add_devices([RestSensor(rest,
+                            config.get('name', DEFAULT_NAME),
+                            config.get('variable'),
+                            config.get('unit_of_measurement'),
+                            config.get('correction_factor', None),
+                            config.get('decimal_places', None))])
+
+
+# pylint: disable=too-many-arguments
+class RestSensor(Entity):
+    """ Implements a REST sensor. """
+
+    def __init__(self, rest, name, variable, unit_of_measurement, corr_factor,
+                 decimal_places):
+        self.rest = rest
+        self._name = name
+        self._variable = variable
+        self._state = 'n/a'
+        self._unit_of_measurement = unit_of_measurement
+        self._corr_factor = corr_factor
+        self._decimal_places = decimal_places
+        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 REST API and updates the state. """
+        self.rest.update()
+        value = self.rest.data
+
+        if 'error' in value:
+            self._state = value['error']
+        else:
+            try:
+                if value is not None:
+                    if self._corr_factor is not None \
+                            and self._decimal_places is not None:
+                        self._state = round(
+                            (float(value[self._variable]) *
+                             float(self._corr_factor)),
+                            self._decimal_places)
+                    elif self._corr_factor is not None \
+                            and self._decimal_places is None:
+                        self._state = round(float(value[self._variable]) *
+                                            float(self._corr_factor))
+                    else:
+                        self._state = value[self._variable]
+            except ValueError:
+                self._state = value[self._variable]
+
+
+# pylint: disable=too-few-public-methods
+class RestDataGet(object):
+    """ Class for handling the data retrieval with GET method. """
+
+    def __init__(self, resource):
+        self._resource = resource
+        self.data = dict()
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """ Gets the latest data from REST service with GET method. """
+        try:
+            response = requests.get(self._resource, timeout=10)
+            if 'error' in self.data:
+                del self.data['error']
+            self.data = response.json()
+        except requests.exceptions.ConnectionError:
+            _LOGGER.error("No route to resource/endpoint.")
+            self.data['error'] = 'N/A'
+
+
+# pylint: disable=too-few-public-methods
+class RestDataPost(object):
+    """ Class for handling the data retrieval with POST method. """
+
+    def __init__(self, resource, payload):
+        self._resource = resource
+        self._payload = payload
+        self.data = dict()
+
+    @Throttle(MIN_TIME_BETWEEN_UPDATES)
+    def update(self):
+        """ Gets the latest data from REST service with POST method. """
+        try:
+            response = requests.post(self._resource, data=self._payload,
+                                     timeout=10)
+            if 'error' in self.data:
+                del self.data['error']
+            self.data = response.json()
+        except requests.exceptions.ConnectionError:
+            _LOGGER.error("No route to resource/endpoint.")
+            self.data['error'] = 'N/A'