[SOLVED] Parsing json and assigning to an item

Setup, Configuration and Use Scripts & Rules
1

  • Platform information:

    • Hardware: RPI 3B
    • OS: openhabian
    • openHAB version: 2.4 latest stable release

  • Issue of the topic: I am retrieving a number value through json and try to assign it to an item. This returns an error: ‘Could not invoke method: org.eclipse.smarthome…sendCommand(org.eclipse.smarthome.core.items.Item,java.lang.Number) on instance: null

Config:

  • Item:

Number testItem “Test item” (testgroup)

  • Rule:

var String json = …some json request…
var int test = transform(“JSONPATH”, “…value”, json)
testItem.sendCommand(test)

I didn’t bother typing it here, but I have obviously logged the hell out of this. The json call returns the correct value, the variable test has a value which seems correct, and it’s really the sendCommand that fails (but only when the value is coming from the json transform, a manually assigned value works fine)

I am kind of getting desperate! Does anyone have an idea where to look?

2

Try this. Also, be careful with the funky double quotes. Might just be a copy/paste thing, but your strings above don’t have the standard double quote character.

    try {
        val Number test = Integer.parseInt(transform("JSONPATH", "...value", json))
        testItem.sendCommand(test)
    } catch (NumberFormatException e) {
        logInfo("test","Caught NumberFormatException: {}", e.getMessage)
    }
3

Hey Mark,

thanks for the suggestion!
Never mind the syntax, I typed it out on my iPad which seems to use those weird double quotes…

I have just tried it and… exactly the same behavior as before, catch is not picking up the error.

2019-05-07 08:44:31.311 [INFO ] [.eclipse.smarthome.model.script.Test] - Number value 5668
2019-05-07 08:44:31.315 [ERROR] [ntime.internal.engine.ExecuteRuleJob] - Error during the execution of rule ‘testJSON’: An error occurred during the script execution: Could not invoke method: org.eclipse.smarthome.model.script.actions.BusEvent.sendCommand(org.eclipse.smarthome.core.items.Item,java.lang.Number) on instance: null

Code used:

try {
var String json = sendHttpGetRequest(url)
var Number test = transform(“JSONPATH”, “$…value”, json)
logInfo(“Test”, "Number value " + test)
testItem.sendCommand(test)
logInfo(“Test”, “Number assigned”)
} catch (NumberFormatException e) {
logInfo(“test”,“Caught NumberFormatException: {}”, e.getMessage)
}

Weird thing is that this works fine…

var Number test = 1
logInfo(“Test”, "Number value " + test)
testItem.sendCommand(test)
logInfo(“Test”, “Number assigned”)

returns:

2019-05-07 08:57:00.150 [INFO ] [.eclipse.smarthome.model.script.Test] - Number value 1
2019-05-07 08:57:00.166 [ome.event.ItemCommandEvent] - Item ‘testItem’ received command 1
2019-05-07 08:57:00.168 [INFO ] [.eclipse.smarthome.model.script.Test] - Number assigned

So ‘something’ weird is going on with the transform.

4

You’re trying to send an int type variable via sendCommand. Note that when it works in your simple test, you send a Number type.
I think the command needs to be a string or easily convertible to a string, but you know that it works with a Number, so …

Okay, that’s rubbish - just read your most recent test properly, where you do use a Number. I’d still try Number.toString in the sendCommand()

5

transform returns a String type, not a Number type. If you were editing your rule in VS Code, you would see multiple errors.

I have this exact test case in a rule and I know it works.

    /* JSONPATH parseInt example */
    val String sJson = '{"state":"ON","brightness":255}'
    try {
        val Number nBright = Integer.parseInt(transform("JSONPATH","$.brightness",sJson))
        val Number converted = (nBright * 100)
        logInfo("test","Converted = " + converted)
        TestItem_Number.sendCommand(converted)
    } catch (NumberFormatException e) {
        logInfo("test","Caught NumberFormatException: {}", e.getMessage)
    }

2019-05-07 06:37:00.138 [INFO ] [.eclipse.smarthome.model.script.test] - TEST: Test rule is executing
2019-05-07 06:37:00.138 [INFO ] [.eclipse.smarthome.model.script.test] - Converted = 25500

openhab> smarthome:items list | grep TestItem_Number                                                                                       
TestItem_Number (Type=NumberItem, State=25500, Label=Test Number, Category=null)
3 Likes
6

Damn, I always forget that doesn’t force a Number type var

7

Yep, in VS Code, that expression generates an error.

Type mismatch: cannot convert from String to Number(org.eclipse.xtext.xbase.validation.IssueCodes.incompatible_types)
8

Ah darn! That looks like a good fix! At work now but I’ll try it tonight!

BTW I do use VS code sometimes, but notepad++ more often. Perhaps this is a good moment to switch :man_facepalming:

Thanks Mark!

9

Yep, that fixed it…

Integer.parseInt()

Thanks again Mark: I would never have thought of this

1 Like