DateTime calculations/formatting in a rule

Setup, Configuration and Use Scripts & Rules
5

One small point: A DateTime item in openHAB is not at all the same thing as a DateTime object from org.joda.time. They unfortunately share the same name, but they aren’t actually related.

A DateTime item in openHAB usually has a state of class DateTimeType. When you have a DateTimeType, you can reference its java.util.Calendar member using .calendar in a rule. Then you can access this calendar’s properties, such as .timeInMillis. Then you can use that returned long to create or modify org.joda.time.base.AbstractInstant instances. For example:

import org.joda.time.*
import org.openhab.core.library.types.DateTimeType

rule MyRule
when
  Item BinMenArrive changed
then
  val DateTime binMenArrive = new DateTime((BinMenArrive.state as DateTimeType).calendar.currentTimeMills)
  if (now.isBefore(binMenArrive)) {
    logInfo("MyRule", "put the bins out!")
  } else {
    logWarn("MyRule", "too late; have to wait a week.")
  }
end