Understanding event.time in JS rules with TimeOfDayTrigger

Setup, Configuration and Use Beginners
1

Hi everyone,

I’m trying to understand how the event.time property is supposed to work in JS rules.

In the openhab-js documentation it says that the event object contains the following property:

time – TimeOfDayTrigger – Time of day value of the trigger

However, in my rule I get undefined.

Example:

logger.info(`Time ${event.time}.`);

Log output:

Time undefined

My rule is triggered by

triggers: [triggers.ItemStateChangeTrigger("Power_House_DeyeActualPower"), triggers.GenericCronTrigger('*/20 * * * * ? *')],

My question is:

  • How should event.time be interpreted in this context?
  • Is it supposed to contain the configured trigger time?
  • Or is there another recommended way to get the time when the rule was triggered?

I would like to understand how event.time is intended to work according to the documentation.

Thanks!

2

As you are using the GenericCronTrigger and not the TimeOfDayTrigger, it is expected to be undefined. The JSDoc says it’s only for TimeOfDayTrigger.

For TimeOfDayTrigger, yes.
For GenericCronTrigger, use .cronExpression. See Global - openHAB JS.

None of the triggering events provides a timestamp, but you can get the current timestamp using time.toZDT() at the beginning of the rule.

3

Why do than need this ?
So what is a possible usage of this?

4

If you have multiple TimeOfDayTriggers you can determine which one triggered the rule based on the .time config value.

5

Note that at least for now, TimeOfDayTrigger is not universally supported. I’m a little behind on GitHub (it’s been a trying couple of weeks, I’ve not had a lot of OH time) but I think it’s just now being added to Rules DSL.

To elaborate a little on @florian-h05’s answer, the overriding requirement is to be able to determine exactly what triggered the rule. Therefore, the event Object contains enough information in it to tie this run of the rule to what triggered it. Since the TimeOfDayTrigger is a different trigger from GenericCronTrigger, the information that’s added to the event Object is going to be different.

Note, this isn’t just to determine what type of trigger caused the rule to run. This is to determine exactly which trigger caused the rule to run. If you have more than one TimeOfDayTrigger or GenericCronTrigger triggers, you can tell the difference between them.

This has many uses. One example is in my rule templates I use this information to change how the rule runs. When it’s triggered by time, cron, or Item event triggers it works as normal. When it’s triggered manually it runs a self test.

You could also use this in cases where you have a rule that needs to do one or two things differently based on how it’s triggered but otherwise work the same. For example, update the states of some Items but when it’s triggered by a TimeOfDayTrigger at midnight also reset some counters.

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