OH 3 Examples: Writing and using JavaScript Libraries in MainUI created Rules

rlkoshak · January 24, 2021, 4:19am

That’s what I was afraid of. I need to fix the library and I need to do a better review next time. A library should save it’s internal logger to this.

drewpetrsn · January 24, 2021, 4:32am

Ah, I see. Do you fix it by “wrapping the function” as you described above in the timeUtils.js?

(function(context) {
…
})(this)

rlkoshak · January 24, 2021, 4:44am

Yes, and then only save things to context that you want available in the rule that loaded the library. Internal stuff used only by the library should be just vars.

drewpetrsn · January 24, 2021, 4:57am

Thank you for your help and explanation!

aitorforero · January 28, 2021, 8:53pm

Hi,

I have started migrating from 2.5 to 3. Mi idea is to write all my rules in javascript.

I have created a rule that uses a timer that when it finish creates another timer in order to execute it self again and again.

Something like this:

function loop() {
if(some condition) stop();

this.timer = ScriptExecution.createTimer( next time, loop);
}

function stop() {
this.timer.cancel();
}

The problem comes when after modifying the code and saving, the handler of the timer is lost and it continues executing without the posibility to cancel it.

I don’t know how to manage with this because the previous context is lost and the handler with it

Any idea how to deal with this?

thanks in advance

rlkoshak · January 28, 2021, 10:31pm

github.com

rkoshak/openhab-rules-tools/blob/main/looping_timer/automation/lib/javascript/community/looping_timer.js

/**
 * Constructor, initializes the logger, imports the needed stuff and creates an empty timer.
 */
var LoopingTimer = function() {
    'use strict';
    var OPENHAB_CONF = java.lang.System.getenv("OPENHAB_CONF");
    this.log = Java.type("org.slf4j.LoggerFactory").getLogger("org.openhab.model.script.Rules.LoopingTimer");
    this.log.debug("Building Looping Timer instance.");
    this.timer;
    this.log.debug("Loading timeUtils");
    load(OPENHAB_CONF+'/automation/lib/javascript/community/timeUtils.js');
    this.ScriptExecution = Java.type("org.openhab.core.model.script.actions.ScriptExecution");
    this.log.debug("Looping Timer is ready to operate");
  }
  
  
  /**
  
   * @param {*} when Optional time when to kick off the first call to function.
              It can be any of the forms supported by to_datetime in time_utils

This file has been truncated. show original

franks · January 29, 2021, 2:01pm

The simple answer is, you can’t. As you already found out, the script context gets destroyed when the script is saved. Because there is currently no other way to store a timer instance, that was created on your behalf, it is lost. You can therefore neither reschedule or cancel this timer and it will fire eventually when it is due.

rlkoshak · January 29, 2021, 3:48pm

There is one exception to that. If you are writing the rules in .js files, assuming they work the same as Python .py files, you can define a scriptUnloaded function that will get called before the rule is destroyed. You can cancel the running timers there.

Note I don’t really know the mechanism behind it. It may be something unique to Python, or something implemented by the Helper Libraries and not something generally available.

I do know that it is true that we cannot do this clean up with UI created rules and that is where I’ve been focusing right now so I’ve a lot of unanswered questions about the mechanism.

CrazyIvan359 · January 29, 2021, 4:07pm

The scriptLoaded and scriptUnloaded calls are done by the Script Engine Container on the OH side, so are language agnostic. That said, I never got anything working in scriptUnloaded in JS.

aitorforero · January 29, 2021, 7:55pm

Thanks for your response.
I think that this class has the same problem that I have said. If the loop function has not a condition to stop itself and the timer only stops when the calling script cancels it, if the script is modified and saved while timer is executing it will not be posible to stop it any more.

rlkoshak · January 29, 2021, 9:01pm

That’s going to always be a problem no matter what. If you use Python rules in .py files you can use scriptUnloaded to cancel the timers when the file is unloaded. Theoretically it should work with JavaScript .js files too but maybe not based on Michael’s experience.

aitorforero · January 30, 2021, 10:21am

Thanks

I’m going to explore then scriptUnloaded function proposed by @rlkoshak. If it does not work I will try to think in other ways to achive it

aitorforero · January 31, 2021, 10:49am

After setting log level:

org.openhab.core.automation.module.script.internal │ TRACE
org.openhab.core.automation.module.script.internal.ScriptEngineManagerImpl │ TRACE

I found out that at least for the scripts stored in files, the scriptUnloaded is called:

function scriptUnloaded() {
   logger.info("Script unloaded!!");
}

2021-01-31 11:23:38.689 [TRACE] [ipt.internal.ScriptEngineManagerImpl] - scriptLoaded() is not defined in the script: file:/openhab/conf/automation/jsr223/javascript/personal/PID.js
2021-01-31 11:24:15.381 [INFO ] [org.openhab.rule.automation.PID ] - Script unloaded!!
2021-01-31 11:24:15.394 [INFO ] [ab.core.service.AbstractWatchService] - Loading script ‘/openhab/conf/automation/jsr223/javascript/personal/PID.js’

When function is not defined, a trace message is written as it can be seen for scripLoaded()

Knowing this, using timer manager that stores timers by name like in the library by @rlkoshak is all that is needed to avoid looping timers running indefinitely. When the script that creates and uses the timer is loaded again, it will retrieve the timer by name. And when the timer library is unloaded, you can cancel all the running timers that otherwise the handlers would be lost.

On the other hand I will try to figure out how to get running the scriptLoaded function for UI rules too

aitorforero · January 31, 2021, 11:13am

I think the reason for scriptUnloaded not being executed in rules is because rules don have their own ScriptEngine. Rules are excuted by scriptEngine.eval(script) and I thing that sctiptEngine is singleton and when the rule changes is not getting unloaded as is done when a file based script changes. Therfore is not possible to define unloadedSctipt function that will get called as the rule changes

jace · February 1, 2021, 1:52am

This might not be the right place to ask, but I was looking through the timeUtils.js for hints. I’m trying to work with a DateTimeType (passed in as a string) in a transformation JS script. The string that gets passed is not valid ISO8601, as the timezone doesn’t contain a colon (ex -0800, not -08:00).

What would be the best way of handling that?

rlkoshak · February 1, 2021, 3:58pm

Thanks for doing the research and experimentation to figure this out and find the edge cases! It’s kind of sad that there is no way to clean up a rule (for now, and issue is probably worth creating to add something like this for UI rules too). But I’m really glad you found how to make it workin for .js files!

EDIT:

github.com/openhab/openhab-core

[automation] Provide equivalent of scriptUnloaded for UI generated rules

opened 04:58PM - 01 Feb 21 UTC

closed 05:56PM - 14 May 22 UTC

rkoshak

enhancement

This is a feature request. When writing rules in Python and JavaScript (and p…robably Groovy as well) one can define a special function called `scriptUnloaded` (there is also a `scriptLoaded` which should be covered by this also. This function gets called when, as the name implies, the script file is unloaded. This function is particularly useful for Timer management and working with rules that create other rules (an advanced but useful use case that is helpful for library developers), dynamically created Items, etc. In this function one can cancel, delete, and otherwise clean up all the stuff the rule created that exists outside the script itself. The most useful thing to do here would be to cancel any running timers created by the script. This capability is missing from UI generated rules. See https://community.openhab.org/t/oh-3-examples-writing-and-using-javascript-libraries-in-mainui-created-rules/108526/33 for some discussion on this. So any Timers or other stuff created by a Script Action that exists outside of the Script Action gets orphaned and continues to exist. In the best case this will result in errors in the logs as orphaned Timers go off. In the worst case it can leave a looping Timer running forever until OH is restarted and a bunch of artifacts (Items, Rules, etc) that were dynamically created that need to be manually cleaned up afterwards. To take one extreme case, there is a Community Library in the Helper Libraries that would consolidate the hourly forecast Items into a daily forecast. This script would create dozens of Items to accomplish this. Now that the daily forecast is supported by the API, if that capability were created in the UI it would require manually deletion of those dozens of no longer needed Items, and the links which could be quite tedious and result in problems like orphaned links which can cause problems themselves.

For this I would probably insert the colon into the String so it becomes ISO8601. That would probably be the easiest. Something like:

var iso8601 = i.slice(0, -2) + ":" + i.slice((i.length - 2), i.length);

Note, I just typed that in, the indices may be wrong. See JavaScript String Methods for the full details on slice.

jace · February 1, 2021, 8:39pm

For anyone that comes across this later, for my case, the DateTime string containing milliseconds was also problematic. Removing those helped:

ISO8601 = ISO8601.replace(ISO8601.match(/\.([0-9])+/g), '');

stefan13 · March 26, 2021, 7:11pm

Hello @rlkoshak - I have a problem to cancel a running LoopTimer.
The timer is running as expected and is terminated as well if the condition in the function is true.

However, when I try to cancel the running timer I see an error message in the log file.

EDIT: I solved the error message - something was wrong in the function.
However, timer still doesn’t terminate when I try to cancel it.

  iLaufzeit = 0;
  
  var countdown = function (){
    
    iLaufzeit += 1;
    
    if(iLaufzeit <= iDauer) {
      events.sendCommand("Bewaesserung_Rasen_LaufzeitAktuell", iLaufzeit );
      return "1m"; }    
    else {      
      events.sendCommand("Bewaesserung_Rasen_Schalter", OFF );      
    }
      
  }

  this.lp.loop(countdown,"1m");

I use below to cancel the timer

   this.lp.cancel();

I added some debugging to the code to see why cancelling doesn’t work.

  /**
   * Cancels the running timer.
   */
  LoopingTimer.prototype.cancel = function() {
    this.log.debug("Looping timer - Canceling");
    this.log.debug("Looping Timer state: " + this.timer );
    this.log.debug("Looping Timer hasTerminated() " + this.timer.hasTerminated() );

      if (this.timer !== undefined && !(this.hasTerminated()) ){
          this.timer.cancel();
          this.log.debug("Looping timer - Canceled");
      }
  }

As below, the timer seems to be undefined, when checking this.timer.
When checking hasTerminated() the script raised a ERROR accordingly.


==> /log/openhab.log <==
2021-03-27 17:35:04.753 [DEBUG] [nhab.model.script.Rules.LoopingTimer] - Looping timer - loop called
2021-03-27 17:35:04.759 [DEBUG] [penhab.model.script.Rules.time_utils] - Converting duration 1m
2021-03-27 17:35:04.768 [DEBUG] [penhab.model.script.Rules.time_utils] - Match = 1m
2021-03-27 17:35:04.776 [DEBUG] [penhab.model.script.Rules.time_utils] - Days = 0 hours = 0 minutes = 1 seconds = 0 msec = 0
==> /log/events.log <==
2021-03-27 17:35:06.948 [INFO ] [openhab.event.ItemCommandEvent      ] - Item 'Bewaesserung_Rasen_Schalter' received command OFF
2021-03-27 17:35:06.948 [INFO ] [openhab.event.ItemStateChangedEvent ] - Item 'Bewaesserung_Rasen_Schalter' changed from ON to OFF
==> /log/openhab.log <==
2021-03-27 17:35:06.950 [INFO ] [enhab.core.model.script.Bewaesserung] -  Bewaesserung AUS - OFF
2021-03-27 17:35:06.951 [DEBUG] [nhab.model.script.Rules.LoopingTimer] - Looping timer - Canceling
2021-03-27 17:35:06.952 [DEBUG] [nhab.model.script.Rules.LoopingTimer] - Looping Timer state: undefined
2021-03-27 17:35:06.952 [ERROR] [internal.handler.ScriptActionHandler] - Script execution of rule with UID '077fd9674d' failed: TypeError: Cannot read property "hasTerminated" from undefined in /openhab/conf/automation/lib/javascript/community/loopingTimer.js at line number 54

rlkoshak · March 29, 2021, 6:52pm

Show the full code. I don’t see where you’ve imported any libraries.

I don’t see the code where this.lp is defined.

I don’t see where this.timer is defined.

stefan13 · March 30, 2021, 6:40am

Hello Rich,

below the full code I use - however I think I found the problem.

The error message only occurs if the function LoopingTimer.prototype.loop for the first iteration of the loop is executed, as this timer is not assigned to this.timer and therefore cannot be canceled, as far as I see.

Would that assumption make sense?

this.OPENHAB_CONF = java.lang.System.getenv("OPENHAB_CONF");
this.logger = (this.logger === undefined) ? Java.type("org.slf4j.LoggerFactory").getLogger("org.openhab.model.script.Rules.LoopingTimer") : this.logger; 
load(OPENHAB_CONF+'/automation/lib/javascript/community/loopingTimer.js');
var Log = Java.type("org.openhab.core.model.script.actions.Log");

this.lp = (this.lp === undefined) ? new LoopingTimer() : this.lp;


var dtStartZeit
var iDauer 
var iLaufzeit 


if (event.itemName === "Bewaesserung_Rasen_Schalter" && items["Bewaesserung_Rasen_Schalter"] === ON){
  
  // Dauer der Bewässerung bei Direktbetrieb ----- (Muss noch für Timerbetrieb angepasst werden)
  iDauer = parseInt(items["Bewaesserung_Rasen_Ausschalt_Timer"]);
  Log.logInfo("Bewaesserung" , "Dauer der Bewässerung " + iDauer + "min" );
  
  // Speichert Startzeit der letzten Bewässerung
  dtStartZeit = Date.now();
    
    
  // Init - Aktuelle Laufzeit
  events.sendCommand('Bewaesserung_Rasen_LaufzeitAktuell', 0);
  
  // Bewaesserung_Rasen_LaufzeitGesamt = Bewaesserung_Rasen_Ausschalt_Timer
  events.sendCommand('Bewaesserung_Rasen_LaufzeitGesamt', items["Bewaesserung_Rasen_Ausschalt_Timer"]);
  
  iLaufzeit = 0;
  
  var countdown = function (){
    
    iLaufzeit += 1;
    events.sendCommand("Bewaesserung_Rasen_LaufzeitAktuell", iLaufzeit );
    Log.logInfo("Bewaesserung" , "Dauer der Bewässerung " + iLaufzeit + "min / " + iDauer + "min" );
    
    if(iLaufzeit < iDauer) {
      
      return "1m"; } 
    
    else {      
      events.sendCommand("Bewaesserung_Rasen_Schalter", OFF );      
    }
      
  }

  this.lp.loop(countdown,"1m");
  
}