Parameters are values which can easily be changed without having to reload the rules. Values will be picked up during runtime as soon as they get edited in the corresponding file. If the file doesn’t exist yet it will automatically be generated in the configured param folder. Parameters are perfect for boundaries (e.g. if value is below param switch something on). Currently there are is Parameter and DictParameter available.

from HABApp import Rule, Parameter
from import ValueChangeEventFilter

class MyRuleWithParameters(Rule):
    def __init__(self):

        # construct parameter once, default_value can be anything
        self.min_value = Parameter( 'param_file_testrule', 'min_value', default_value=10)

        # deeper structuring is possible through specifying multiple keys
        self.min_value_nested = Parameter(
            'Rule A', 'subkey1', 'subkey2',
            default_value=['a', 'b', 'c'] # defaults can also be dicts or lists

        self.listen_event('test_item', self.on_change_event, ValueChangeEventFilter())

    def on_change_event(self, event):

        # the parameter can be used like a normal variable, comparison works as expected
        if self.min_value < event.value:

        # The current value can be accessed through the value-property, but don't cache it!
        current_value = self.min_value.value


Created file:

min_value: 10
Rule A:
            - a
            - b
            - c

Changes in the file will be automatically picked up through Parameter.


Since parameters used to provide flexible configuration for automation classes they can get quite complex and error prone. Thus it is possible to provide a validator for a file which will check the files for constraints, missing keys etc. when the file is loaded.

set_file_validator(filename, validator, allow_extra_keys=True)

Add a validator for the parameter file. If the file is already loaded this will reload the file.

  • filename (str) – filename which shall be validated (without extension)

  • validator (Any) – Description of file content - see the library voluptuous for examples. Use None to remove validator.

  • allow_extra_keys – Allow additional keys in the file structure


import HABApp
import voluptuous

# Validator can even and should be specified before loading rules

# allows a dict e.g. { 'key1': {'key2': '5}}
HABApp.parameters.set_file_validator('file1', {str: {str: int}})

# More complex example with an optional key:
validator = {
    'Test': int,
    'Key': {
        'mandatory_key': str,
        voluptuous.Optional('optional'): int
HABApp.parameters.set_file_validator('file1', validator)

Create rules from Parameters

Parameteres are not bound to rule instance and thus work everywhere in the rule file. It is possible to dynamically create rules from the contents of the parameter file.

It’s even possible to automatically reload rules if the parameter file has changed: Just add the “reloads on” entry to the file.

   v: 10
   v: 12


import HABApp

class MyRule(HABApp.Rule):
    def __init__(self, k, v):

        print(f'{k}: {v}')

cfg = HABApp.DictParameter('my_param')    # this will get the file content
for k, v in cfg.items():
    MyRule(k, v)
key1: {'v': 10}
key2: {'v': 12}

Parameter classes

class Parameter(filename, *keys, default_value='ToDo')
property value: Any

Return the current value. This will do the lookup so make sure to not cache this value, otherwise the parameter might not work as expected.

class DictParameter(filename, *keys, default_value='ToDo')

Implements a dict interface

property value: dict

Return the current value. This will do the lookup so make sure to not cache this value, otherwise the parameter might not work as expected.