Support parsing mqtt messages via jsonpath

homeassistant/components/mqtt/__init__.py

@@ -9,6 +9,8 @@ https://home-assistant.io/components/mqtt/
 import logging
 import os
 import socket
+import json
+import jsonpath_rw
 
 from homeassistant.exceptions import HomeAssistantError
 import homeassistant.util as util
@@ -127,6 +129,15 @@ def setup(hass, config):
     return True
 
 
+class JsonFmtParser(object):
+  """ Implements a json parser on xpath"""
+  def __init__(self, jsonpath):
+    self._expr = jsonpath_rw.parse(jsonpath)
+  def __call__(self, payload):
+    match = self._expr.find(json.loads(payload))
+    return match[0].value if len(match) > 0 else None
+
+
 # This is based on one of the paho-mqtt examples:
 # http://git.eclipse.org/c/paho/org.eclipse.paho.mqtt.python.git/tree/examples/sub-class.py
 # pylint: disable=too-many-arguments

homeassistant/components/sensor/mqtt.py

@@ -7,6 +7,8 @@ For more details about this platform, please refer to the documentation at
 https://home-assistant.io/components/sensor.mqtt/
 """
 import logging
+import json
+import jsonpath_rw
 from homeassistant.helpers.entity import Entity
 import homeassistant.components.mqtt as mqtt
 
@@ -31,23 +33,30 @@ def setup_platform(hass, config, add_devices_callback, discovery_info=None):
         config.get('name', DEFAULT_NAME),
         config.get('state_topic'),
         config.get('qos', DEFAULT_QOS),
-        config.get('unit_of_measurement'))])
+        config.get('unit_of_measurement'),
+        config.get('state_format'))])
 
 
 # pylint: disable=too-many-arguments, too-many-instance-attributes
 class MqttSensor(Entity):
     """ Represents a sensor that can be updated using MQTT. """
-    def __init__(self, hass, name, state_topic, qos, unit_of_measurement):
+    def __init__(self, hass, name, state_topic, qos, unit_of_measurement,state_format):
         self._state = "-"
         self._hass = hass
         self._name = name
         self._state_topic = state_topic
         self._qos = qos
         self._unit_of_measurement = unit_of_measurement
+        self._state_format = state_format
+        
+        if self._state_format.startswith('json:'):
+          self._parser = mqtt.JsonFmtParser(self._state_format[5:])
+        else:
+          self._parser = lambda x: x
 
         def message_received(topic, payload, qos):
             """ A new MQTT message has been received. """
-            self._state = payload
+            self._state = self._parser(payload)
             self.update_ha_state()
 
         mqtt.subscribe(hass, self._state_topic, message_received, self._qos)

homeassistant/components/switch/mqtt.py

@@ -37,14 +37,15 @@ def setup_platform(hass, config, add_devices_callback, discovery_info=None):
         config.get('qos', DEFAULT_QOS),
         config.get('payload_on', DEFAULT_PAYLOAD_ON),
         config.get('payload_off', DEFAULT_PAYLOAD_OFF),
-        config.get('optimistic', DEFAULT_OPTIMISTIC))])
+        config.get('optimistic', DEFAULT_OPTIMISTIC),
+        config.get('state_format'))])
 
 
 # pylint: disable=too-many-arguments, too-many-instance-attributes
 class MqttSwitch(SwitchDevice):
     """ Represents a switch that can be togggled using MQTT. """
     def __init__(self, hass, name, state_topic, command_topic, qos,
-                 payload_on, payload_off, optimistic):
+                 payload_on, payload_off, optimistic, state_format):
         self._state = False
         self._hass = hass
         self._name = name
@@ -54,9 +55,17 @@ class MqttSwitch(SwitchDevice):
         self._payload_on = payload_on
         self._payload_off = payload_off
         self._optimistic = optimistic
+        
+        self._state_format = state_format
+        
+        if self._state_format.startswith('json:'):
+          self._parser = mqtt.JsonFmtParser(self._state_format[5:])
+        else:
+          self._parser = lambda x: x
 
         def message_received(topic, payload, qos):
             """ A new MQTT message has been received. """
+            payload = self._parser(payload)
             if payload == self._payload_on:
                 self._state = True
                 self.update_ha_state()

requirements_all.txt

@@ -74,6 +74,7 @@ https://github.com/bashwork/pymodbus/archive/d7fc4f1cc975631e0a9011390e8017f64b6
 
 # homeassistant.components.mqtt
 paho-mqtt==1.1
+jsonpath-rw==1.4.0
 
 # homeassistant.components.notify.pushbullet
 pushbullet.py==0.9.0