homie.property — Homie Property

This module provides an interface to the Homie Node Property definition.

class HomieProperty()

A property object is used to define a homie node property. A property object must be attached to a node object.

Usage Model:

from homie.property import HomieProperty
from homie.constants import BOOLEAN, FALSE, TRUE

power_property = HomieProperty(


class homie.property.HomieNodeProperty(id, name=None, settable=False, retained=True, unit=None, datatype=STRING, format=None, default=None, restore=True)

The arguments id, name, settable, retained, unit, datatype and format are arguments from the Homie convention definition for property attributes with the same defaults.

The arguments default, restore, on_message are Microhomie specific.

The arguments are:

  • id is mandatory and must be a unique property ID on a per-node basis.
  • name specifies the a friendly name of the property.
  • settable allows a property to be settable and enables the /set topic. Default is False.
  • retained specifies if the property is a retained message. Default is True.
  • unit optional unit of this proeprty.
  • datatype specifies the data type as string. Allowed data types are string, integer, float, boolean, enum, color. This types can be importet from homie.constants. Default is STRING.
  • format specifies restrictions or options for the given data type. Default is None.
    • For integer and float: Describes a range of payloads e.g. 10:15
    • For enum: payload,payload,payload for enumerating all valid payloads.
    • For color:
      • rgb to provide colors in RGB format e.g. 255,255,0 for yellow.
      • hsv to provide colors in HSV format e.g. 60,100,100 for yellow.
  • default set the default message payload. Default is None.
  • restore restore property payload from mqtt retained message. Default is True.
  • on_message callback method when the property receives new data.
  • pub_on_upd publish or not publish when the proptery value changes, default is to publish on each value assignment.



This is where the property data/payload is stored. The value will be auto published if assigned and self.pub_on_upd is True. Set self.pub_on_upd to False to only publish the value when the value changes.



This method generate the homie property topic and will be called when the node is added to the device.


This method publishes the current property value to mqtt. None values will not be published.


Subscribe to the property topics.

HomieProperty.restore_handler(self, topic, payload, retained)

Gets called when the property should be restored from mqtt.

After called, this method removes the restore_handler callback and un-subscribe from the topic. When the restored value is valid it will be assigned to the value attribute without publishing the change to mqtt.

The arguments are:

  • topic the message topic.
  • payload the message payload.
  • retained specifies if the payload is retained.
HomieProperty.message_handler(self, topic, payload, retained)

Retained messages are not allowed on this topic, if retained message the function will return early.

This method handles incoming payload for the property. Per default this method validates the payload and updates the object value with the new payload.

To overwrite the default handler set a on_message handler when adding the property to the node. See HomieNode.add_property().

The arguments are:

  • topic the message topic.
  • payload the message payload.
  • retained specifies if the payload is retained.

This method publishes all homie property attributes to mqtt on device init.

Useful constants

The following constants can be used for the datatype argument.