Changing string item to number type in rule?

Setup, Configuration and Use Beginners
1

Gday,

Just trying to get up an alert when a phone battery is getting low. I followed along from this thread (which I think is really awesome) and parsed the battery value from the owntracks mqtt data.

The rest item seems to be updating ok, but is a string type

Item is,
String mqttNWBattery “NW’s Battery [%s%%]”

Rule is,

rule "Battery Alert NW"
when
	Item mqttNWBattery changed 

then
	if((mqttNWBattery.state) < 25){
		sendMail("myemail@gmail.com", "NW battery <25%!", "")
	}
end

I presume I need to change the string item to a decimal type before checking it in the rule math? Not sure how to do that bit.
Could someone point me in the right direction?

Kind Regards,
George

2

If it is an integer value (i.e. no decimal place) you can do this in your rule:

if(Integer::parseInt(mqttNWBattery.state) < 25)

If it does have a decimal point use Double::parseDouble() instead

However, if you make your Item a Number instead of a String OH should be able to parse the value for you, as long as the String is a parseable number (e.g. no leading or trailing spaces) it will convert it to a DecimalType for you. And if there is something a little off about it you can use a transform to fix it. Then you can do:

if((mqttNWBattery.state as DecimalType) < 25)
1 Like
3

Rich,

Thanks for your help, I added the line but it gives me an error when the rule is triggered.

Error:
2016-01-28 17:49:47.966 [ERROR] [o.o.c.s.ScriptExecutionThread ] - Error during the execution of rule ‘Battery Alert NW’: Could not invoke method: java.lang.Integer.parseInt(java.lang.String) on instance: null

Do I need to import anything at the top of the rules file?

    rule "Battery Alert NW"
when
	Item mqttNWBattery changed  
	
then
	if(Integer::parseInt(mqttNWBattery.state) < 25){
		sendMail("myemail@gmail.com", "NW battery <25%!", "")
	}
end

Regards,
George

4

Probably import java.lang.Integer.* should do it :slightly_smiling:

5

George, is there a reason that your item mqttNWBattery is not a Number item? Following from the other thread, if you define the item as a Number, and then in your mqttPositionPatrikRaw rule you

mqttNWBattery.postUpdate(new DecimalType(transform("JSONPATH", "$.batt", json)))

then your “Battery Alert NW” rule can look like this:

rule "Battery Alert NW"
when
  Item mqttNWBattery changed 
then
  if ((mqttNWBattery.state as DecimalType) < 25) {
    sendMail("myemail@gmail.com", "NW battery is " + mqttNWBattery.state.toString + "%", "")
  }
end
6

Thanks heaps for the pointers.

Hmmm the only reason for mqttNWBattery not being a Number item is my lack of understanding. Just changed it and it worked.

I pretend I am reasonably tech savy but certainly not a programmer. It has been enjoyable to get a few things up and running, thanks again.

Regards,
George

1 Like