Rule

Interacting with items

Items are like variables. They have a name and a value (which can be anything). Items from openhab use the item name from openhab and get created when HABApp successfully connects to openhab or when the openhab configuration changes. Items from MQTT use the topic as item name and get created as soon as a message gets processed.

Some item types provide convenience functions, so it is advised to always set the correct item type.

The preferred way to get and create items is through the class factories get_item and get_create_item since this ensures the proper item class and provides type hints when using an IDE!

Example:

from HABApp.core.items import Item
my_item = Item.get_create_item('MyItem', initial_value=5)   # This will create the item if it does not exist
my_item = Item.get_item('MyItem')                           # This will raise an exception if the item is not found
print(my_item)

If an item value gets set there will be a ValueUpdateEvent on the event bus. If it changes there will be additionally a ValueChangeEvent, too.

It is possible to check the item value by comparing it

from HABApp.core.items import Item
my_item = Item.get_item('MyItem')

# this works
if my_item == 5:
    pass    # do something

# and is the same as this
if my_item.value == 5:
    pass    # do something

An overview over the item types can be found on the HABApp item section, the openhab item section and the the mqtt item section

Events

It is possible to listen to events through the listen_event() function. The passed function will be called as soon as an event occurs and the event will pe passed as an argument into the function.

There is the possibility to reduce the function calls to a certain event type with an additional parameter (typically ValueUpdateEvent or ValueChangeEvent).

An overview over the events can be found on the HABApp event section, the openhab event section and the the mqtt event section

Example

from HABApp import Rule
from HABApp.core.events import ValueChangeEvent, ValueUpdateEvent
from HABApp.core.items import Item

class MyRule(Rule):
    def __init__(self):
        super().__init__()
        self.listen_event('MyOpenhabItem', self.on_change, ValueChangeEvent)    # will trigger only on ValueChangeEvent
        self.listen_event('My/MQTT/Topic', self.on_update, ValueUpdateEvent)    # will trigger only on ValueUpdateEvent

        # If you already have an item you can and should use the more convenient method of the item
        # to listen to the item events
        my_item = Item.get_item('MyItem')
        my_item.listen_event(self.on_change, ValueUpdateEvent)

    def on_change(self, event: ValueChangeEvent):
        assert isinstance(event, ValueChangeEvent), type(event)

    def on_update(self, event: ValueUpdateEvent):
        assert isinstance(event, ValueUpdateEvent), type(event)

MyRule()

Additionally there is the possibility to filter not only on the event type but on the event values, too. This can be achieved by passing an instance of EventFilter as event type. There are convenience Filters (e.g. ValueUpdateEventFilter and ValueChangeEventFilter) for the most used event types that provide type hints.

class HABApp.core.events.EventFilter(event_type, **kwargs)
class HABApp.core.events.ValueUpdateEventFilter(value)
class HABApp.core.events.ValueChangeEventFilter(value=<Missing>, old_value=<Missing>)

Example

from HABApp import Rule
from HABApp.core.events import EventFilter, ValueUpdateEventFilter, ValueUpdateEvent
from HABApp.core.items import Item

class MyRule(Rule):
    def __init__(self):
        super().__init__()
        my_item = Item.get_item('MyItem')

        # This will only call the callback for ValueUpdateEvents where the value==my_value
        my_item.listen_event(self.on_val_my_value, ValueUpdateEventFilter(value='my_value'))

        # This is the same as above but with the generic filter
        my_item.listen_event(self.on_val_my_value, EventFilter(ValueUpdateEvent, value='my_value'))

    def on_val_my_value(self, event: ValueUpdateEvent):
        assert isinstance(event, ValueUpdateEvent), type(event)

MyRule()

Scheduler

With the scheduler it is easy to call functions in the future or periodically. Do not use time.sleep but rather run_in().

Function

Description

run_soon()

Run the callback as soon as possible (typically in the next second).

run_in()

Run the callback in x seconds.

run_at()

Run a function at a specified date_time

run_every()

Run a function periodically

run_minutely()

Run a function every minute

run_hourly()

Run a function every hour

run_daily()

Run a function every day

run_on_every_day()

Run a function at a specific time every day

run_on_workdays()

Run a function at a specific time on workdays

run_on_weekends()

Run a function at a specific time on weekends

run_on_day_of_week()

Run a function at a specific time on specific days of the week

run_on_sun()

Run a function in relation to the sun (e.g. Sunrise, Sunset)

All functions return an instance of ScheduledCallbackBase

class HABApp.rule.scheduler.base.ScheduledCallbackBase(callback, *args, **kwargs)
earliest(time_obj)

Set earliest boundary as time of day. None will disable boundary.

Parameters

time_obj (Optional[time]) – time obj, scheduler will not run earlier

Return type

ScheduledCallbackBase

latest(time_obj)

Set earliest boundary as time of day. None will disable boundary.

Parameters

time_obj (Optional[time]) – time obj, scheduler will not run later

Return type

ScheduledCallbackBase

offset(timedelta_obj)

Set a constant offset to the calculation of the next run. None will disable the offset.

Parameters

timedelta_obj (Optional[timedelta]) – constant offset

Return type

ScheduledCallbackBase

jitter(secs)

Add a random jitter per call in the intervall [(-1) * secs … secs] to the next run. None will disable jitter.

Parameters

secs (Optional[int]) – jitter in secs

Return type

ScheduledCallbackBase

boundary_func(func)

Add a function which will be called when the datetime changes. Use this to implement custom boundaries. Use None to disable the boundary function.

Parameters

func (Optional[Callable[[datetime], datetime]]) – Function which returns a datetime obj, arg is a datetime with the next call time

get_next_call()

Return the next execution timestamp

check_due(now)

Check whether the callback is due for execution

Parameters

now (datetime) –

Returns

execute()

Try to execute callback. If the callback is not due yet or execution has already finished nothing will happen

Return type

bool

Returns

True if callback has been executed else False

cancel()

Cancel execution

Running external tools

External tools can be run with the execute_subprocess() function. Once the process has finished the callback will be called with an FinishedProcessInfo instance as first argument. Example:

import HABApp

class MyExecutionRule(HABApp.Rule):

    def __init__(self):
        super().__init__()

        self.execute_subprocess( self.func_when_finished, 'path_to_program', 'arg1', capture_output=True)

    def func_when_finished(self, process_info):
        assert isinstance(process_info, HABApp.rule.FinishedProcessInfo)
        print(process_info)

MyExecutionRule()
class HABApp.rule.FinishedProcessInfo(returncode, stdout, stderr)

Information about the finished process.

Variables
  • returncode (int) – Return code of the process (0: IO, -1: Exception while starting process)

  • stdout (str) – Standard output of the process or None

  • stderr (str) – Error output of the process or None

How to properly use rules from other rule files

This example shows how to properly get a rule during runtime and execute one of its function. With the proper import and type hint this method provides syntax checks and auto complete.

Rule instances can be accessed by their name (typically the class name). In the HABApp.log you can see the name when the rule is loaded. If you want to assign a custom name, you can change the rule name easily by assigning it to self.rule_name in __init__.

Important

Always look up rule every time, never assign to a class member! The rule might get reloaded and then the class member will still point to the old unloaded instance.

rule_a.py:

import HABApp

class ClassA(HABApp.Rule):
    ...

    def function_a(self):
      ...

ClassA()

rule_b.py:

import HABApp
import typing

if typing.TYPE_CHECKING:            # This is only here to allow
    from .rule_a import ClassA      # type hints for the IDE

class ClassB(HABApp.Rule):
    ...

    def function_b(self):

        r = self.get_rule('ClassA')  # type: ClassA
        # The comment "# type: ClassA" will signal the IDE that the value returned from the
        # function is an instance of ClassA and thus provide checks and auto complete.

        # this calls the function on the instance
        r.function_a()

All available functions

class HABApp.Rule
Variables
post_event(name, event)

Post an event to the event bus

Parameters
  • name – name or item to post event to

  • event – Event class to be used (must be class instance)

Returns

listen_event(name, callback, event_type=<class 'HABApp.core.events.events.AllEvents'>)

Register an event listener

Parameters
  • name (Union[BaseValueItem, str]) – item or name to listen to. Use None to listen to all events

  • callback (Callable[[Any], Any]) – callback that accepts one parameter which will contain the event

  • event_type (Union[Type[AllEvents], EventFilter, Any]) – Event filter. This is typically ValueUpdateEvent or ValueChangeEvent which will also trigger on changes/update from openhab or mqtt. Additionally it can be an instance of EventFilter which additionally filters on the values of the event. There are also templates for the most common filters, e.g. ValueUpdateEventFilter and ValueChangeEventFilter

Return type

EventBusListener

execute_subprocess(callback, program, *args, capture_output=True)

Run another program

Parameters
  • callback – Function which will be called after process has finished. First parameter will be an instance of FinishedProcessInfo

  • program – program or path to program to run

  • args – Positional arguments that will be passed to the function

  • capture_output – Capture program output, set to False to only capture return code

Returns

run_every(time, interval, callback, *args, **kwargs)

Run a function periodically

Parameters
  • time (Union[None, datetime, timedelta, time]) – Use a datetime.time object to specify a certain time of day, a datetime.timedelta object to specify a time in the future or None to use the current time.

  • interval (Union[int, timedelta]) –

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

ReoccurringScheduledCallback

run_on_sun(sun_event, callback, *args, run_if_missed=False, **kwargs)

Run a function on sunrise/sunset etc

Parameters
  • sun_event (str) – ‘sunrise’, ‘sunset’, ‘dusk’, ‘dawn’

  • run_if_missed – run the event if we missed it for today

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

SunScheduledCallback

run_on_day_of_week(time, weekdays, callback, *args, **kwargs)
Parameters
  • time (time) – datetime.time

  • weekdays

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

DayOfWeekScheduledCallback

run_on_every_day(time, callback, *args, **kwargs)
Parameters
  • time (time) – datetime.time

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

DayOfWeekScheduledCallback

run_on_workdays(time, callback, *args, **kwargs)
Parameters
  • time (time) – datetime.time

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

DayOfWeekScheduledCallback

run_on_weekends(time, callback, *args, **kwargs)
Parameters
  • time (time) – datetime.time

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

DayOfWeekScheduledCallback

run_daily(callback, *args, **kwargs)

Picks a random hour, minute and second and runs the callback every day

Parameters
  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

ReoccurringScheduledCallback

run_hourly(callback, *args, **kwargs)

Picks a random minute and second and run the callback every hour

Parameters
  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

ReoccurringScheduledCallback

run_minutely(callback, *args, **kwargs)

Picks a random second and runs the callback every minute

Parameters
  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

ReoccurringScheduledCallback

run_at(date_time, callback, *args, **kwargs)

Run a function at a specified date_time

Parameters
  • date_time (Union[None, datetime, timedelta, time]) –

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

OneTimeCallback

run_in(seconds, callback, *args, **kwargs)

Run the callback in x seconds

Parameters
  • seconds (int) – Wait time in seconds or a timedelta obj before calling the function

  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

OneTimeCallback

run_soon(callback, *args, **kwargs)

Run the callback as soon as possible (typically in the next second).

Parameters
  • callback – Function which will be called

  • args – Positional arguments that will be passed to the function

  • kwargs – Keyword arguments that will be passed to the function

Return type

OneTimeCallback

register_on_unload(func)

Register a function with no parameters which will be called when the rule is unloaded. Use this for custom cleanup functions.

Parameters

func (Callable[[], Any]) – function which will be called

register_cancel_obj(obj)

Add a weakref to an obj which has a cancel function. When the rule gets unloaded the cancel function will be called (if the obj was not already garbage collected)

Parameters

obj