Why won't this rule work?

Setup, Configuration and Use Runtime
1

I’m still struggling with Xtend…

rule "Set Laundry Value"
    when
        Item virtual_sensor_minute changed
    then
		if (virtual_sensor_washer_vibrations.state instanceof DecimalType) {
		    var int y = (virtual_sensor_washer_vibrations.state as DecimalType).intValue
		}
		else {
		    var int y = 0}
		       if (sensor_laundry_washer.state > 220)  
        {
        		y = y + 1
                postUpdate(virtual_sensor_washer_vibrations,0)
        } 
        else  
        {		
        		y = y - 1
                postUpdate(virtual_sensor_washer_vibrations,0)
        }
       if (virtual_sensor_washer_vibrations.state > 5)  
        {
                postUpdate(virtual_sensor_washer_switch,ON)
        } 
        else
        {
                postUpdate(virtual_sensor_washer_switch,OFF)
        }

    end

Item
Number virtual_sensor_washer_vibrations "Vibrations: [%s]"

Error
Error during the execution of rule 'Set Laundry Value': An error occured during the script execution: The name 'y' cannot be resolved to an item or type.

2

Curly brackets denote a context. Anything defined inside curly brackets only exist for that context and goes away outside the context.

To define a variable you start with the keyword var or val.

In the above you have your variable definition for y inside curly brackets which means y ceases to exist when you get to your second set of if else statements.

To fix it, declare y outside the first if else statements.

    var int y = 0
    if (Yada Yada yada) {
        y = (virtual blah blah blah)
    }

This concept of scope is pretty universal to most programming languages. Those with a C heritage use curly brackets while other languages use other approaches (e.e. python uses indentation).

4

I may be wrong, but I think, you have an issue in your rule, because virtual_sensor_washer_vibrations will never count up or down, but stay at 0.
That should be better:

rule "Set Laundry Value"
when
    Item virtual_sensor_minute changed
then
    if (!(virtual_sensor_washer_vibrations.state instanceof DecimalType))
        virtual_sensor_washer_vibrations.postUpdate(0)                    //if not initialized set to 0

    if (sensor_laundry_washer.state > 220)
        virtual_sensor_washer_vibrations.postUpdate((virtual_sensor_washer_vibrations.state as DecimalType) + 1)
    else
        virtual_sensor_washer_vibrations.postUpdate((virtual_sensor_washer_vibrations.state as DecimalType) - 1)

    if (virtual_sensor_washer_vibrations.state as DecimalType > 5)  
        virtual_sensor_washer_switch.postUpdate(ON)
    else
        virtual_sensor_washer_switch.postUpdate(OFF)
end
5

Thank you, gentlemen, and apologies for the slow response. 4th of July weekend over here got busy.

In addition to the curly brackets indicating a context, are they treated as one whole statement in an if/then statement? There is no ‘endif’ that I can make work, so I assume when I do

if ()
{}
else
{}
next command

that next command is being executed after the if command regardless of which condition got met.

I’m a pretty good cut/paste scripture between python, bash, javascript and others, but I seem to be having trouble here. Especially when trying to control flow with item states and values. I think I need to go back to basics… need more time as well!

6

But more frustratingly,

Things that work one moment, fail a few minutes later once I add more code, and then I rewind to where it worked previously, and it still doesn’t, so I reboot and now I’m getting that interpreter error:

2016-07-06 10:09:56.834 [WARN ] [el.core.internal.ModelRepositoryImpl] - Configuration model '._standard.rules' is either empty or cannot be parsed correctly! 2016-07-06 10:10:00.487 [ERROR] [.script.engine.ScriptExecutionThread] - Error during the execution of rule 'ConvertMQTTTemp': Script interpreter couldn't be obtain 2016-07-06 10:10:00.509 [ERROR] [.script.engine.ScriptExecutionThread] - Error during the execution of rule 'Set Washer Status': Script interpreter couldn't be obtain

the ‘set washer status’ rule is not even in standard.rules when this error is thrown.

So frustrating, and I’m wasting so much time when I think something will be simple. Guess that is beta software, though…

7

Correct. the “}” serves the same purpose as endif in other languages.

But note that if you do not supply the “{” it is invalid to use a “}”. In that case the only statement that is part of the if context is the line immediately following it. Therefore:

if(conditional)
    one line of code

is equivalent to

if(conditional) {
    one line of code
}

I don’t know OH 2 errors so I can’t be much help there except to suggest this might be caused by a syntax error in your rules file which is causing havoc with the script engine. This could be a mismatched curly bracket (i.e. a { without a matching }) or something like that. You might try getting Designer to load the rule and see if it highlights any syntax errors.

8

Hi Rich,

Thanks as always for the awesome responses. You are clearly instrumental in pushing these technologies forward.

I need to play with Designer more, but feel comfortable editing the text and had trouble with Designer early on. Too many challenges - too many things to do.