Jsonpath parsing of NOAA Aurora fails with IllegalArgumentException

[lagom (Nils)]

Hello community colleagues

hopefully you can help me with an issue that I have regarding jsonpath items.

With OH 2.5 I want to parse the probability of Aurora events for a certain location into items by using the JSON provides by NOAA: https://services.swpc.noaa.gov/json/ovation_aurora_latest.json.

I have the following entries in the http.cfg:

auroraNoaaGov.url=https://services.swpc.noaa.gov/json/ovation_aurora_latest.json
auroraNoaaGov.updateInterval=300000 

My items file has those entires:

Number		AuroraPropabilityHome		"Aurora Home [%.0f%%]"		<home>				{http="<[auroraNoaaGov:300000:JSONPATH($.coordinates[?(@[0] == 51 && @[1] == 6)].2)]" } 
Number		AuroraPropabilityOther		"Aurora Other [%.0f%%]"		<other>				{http="<[auroraNoaaGov:300000:JSONPATH($.coordinates[?(@[0] == 57 && @[1] == 15)].2)]" } 

I successfully tested the JSONPATH at Online JSON Query Tester (jsonquerytool.com) using the Goessner 0.8.0 transform and it succeeded:

My logfiles have the following error:

2021-11-06 11:15:10.497 [ERROR] [b.core.service.AbstractActiveService] - Error while executing background thread HTTP Refresh Service

java.lang.IllegalArgumentException: given transformation function 'JSONPATH($.coordinates[?(@[0' does not follow the expected pattern '<function>(<pattern>)'

	at org.openhab.binding.http.internal.HttpBinding.splitTransformationConfig(HttpBinding.java:261) ~[?:?]

	at org.openhab.binding.http.internal.HttpBinding.execute(HttpBinding.java:211) ~[?:?]

	at org.openhab.core.binding.AbstractActiveBinding$BindingActiveService.execute(AbstractActiveBinding.java:146) ~[bundleFile:?]

	at org.openhab.core.service.AbstractActiveService$RefreshThread.run(AbstractActiveService.java:169) [bundleFile:?]

Where is my fault - I don’t see it.
Could you please help?

[rossko57]

I’d say it has fallen down at the nested closing square bracket ]
Don’t think I’ve ever seen nested [ ] used with OH JSONPATH transformation.

[lagom (Nils)]

Thanks for this hint - but evaluation either with the one mentioned above or with jsonpath online evaluator failed.
Is there a better way to search for values in multidimensional indexed-only arrays?

[rossko57]

Use a technique for playing in a rule to try your JSONPATH params.

val rawjson = '{"Observation Time": "2021-11-06T11:06:00Z", "Forecast Time": "2021-11-06T11:52:00Z", "Data Format": "[Longitude, Latitude, Aurora]", "coordinates": [[0, -90, 5], [0, -89, 0]] }'
var results = transform("JSONPATH", "$.coordinates.[1].[1]", rawjson)
logInfo("test", " simple path to one value: " + results)
results = transform("JSONPATH", "$.coordinates.[?(@.[1]=='-89')].[1]", rawjson)
logInfo("test", " selective path to one value: " + results)

Partial example of searching

Jsonpath issue / data format?

No, it was for our benefit. We cannot see what you see. JSONPATH transformation service is not JSONPATH, and has differences e.g. in the way it handles arrays. The return is always just a plain string, for example. The following params works for me - // test data, just two states val rawjson = '[{"Jurisdiction":"Alabama","Range":"5001 to 10000","Cases Reported":5831,"Community Transmission":"Yes, defined area(s)","URL": "http://www.adph.org/"},{"Jurisdiction":"Alaska","Range":"101 to 1000…

[lagom (Nils)]

Thank you for this tipp.

I created the following rule:

rule "Aurora Test"
when 
	Time cron "0 0/2 * * * ? *"
then
	val rawjson = '{"Observation Time": "2021-11-06T11:06:00Z", "Forecast Time": "2021-11-06T11:52:00Z", "Data Format": "[Longitude, Latitude, Aurora]", "coordinates": [[57, 15, 80], [51, 6, 70], [0, -90, 5], [0, -89, 0]] }'
	var results = transform("JSONPATH", "$.coordinates.[1].[2]", rawjson)
	logInfo("[HDMX] Aurora Test", "Simple path to one value: " + results)
	
	results = transform("JSONPATH", "$.coordinates.[?(@.[1]=='-89')].[2]", rawjson)
	logInfo("[HDMX] Aurora Test", "Selective path to one value: " + results)
	
	results = transform("JSONPATH", "$.coordinates.[?(@[0] == 57 && @[1] == 15)].[2]", rawjson)
	logInfo("[HDMX] Aurora Test", "Desired path to one value: " + results)
	
	results = transform("JSONPATH", "$['coordinates'].[?(@[0] == 57 && @[1] == 15)].[2]", rawjson)
	logInfo("[HDMX] Aurora Test", "Another try: " + results)
end

The output is as follows:

2021-11-06 13:56:00.002 [INFO ] [home.model.script.[HDMX] Aurora Test] - Simple path to one value: 70
2021-11-06 13:56:00.003 [INFO ] [home.model.script.[HDMX] Aurora Test] - Selective path to one value: 0
2021-11-06 13:56:00.003 [INFO ] [home.model.script.[HDMX] Aurora Test] - Desired path to one value: 80
2021-11-06 13:56:00.004 [INFO ] [home.model.script.[HDMX] Aurora Test] - Another try: 80

Assuming that it works, I tried both variants “$.coordinates.[?(@[0] == 57 && @[1] == 15)].[2]” and “$[‘coordinates’].[?(@[0] == 57 && @[1] == 15)].[2]” with the item:

Number		AuroraPropabilityOther		"Aurora Other [%.0f%%]"	{http="<[auroraNoaaGov:10000:JSONPATH($.coordinates.[?(@[0] == 57 && @[1] == 15)].[2])]" }

But it this fails with “java.lang.IllegalArgumentException: given transformation function ‘JSONPATH($[‘coordinates’].[?(@[0’ does not follow the expected pattern ‘()’”

If I use simple path like the following, it works fine:

Number		AuroraPropabilityHome		"Aurora Home [%.0f%%]"	{http="<[auroraNoaaGov:300000:JSONPATH($['coordinates'].[9327].[2])]" }

But as I don’t not if the index will change, I will use a rule for filling the values into the items - not what I prefer, but its ok.

[rossko57]

Something funny about the way the Item definition parser is reading your JSONPATH parameters,

@lagom

JSONPATH($.coordinates.[?(@[0] == 57

it’s going wrong around the closing ]
Try removing all those extraneous spaces.

[lagom (Nils)]

Perfect, thank you!!!

I removed the spaces and now the JsonPath works fine:

Number	AuroraPropabilityOther	"Aurora Other [%.0f%%]"	{http="<[auroraNoaaGov:300000:JSONPATH($.coordinates[?(@[0]==57 && @[1]==15)].[2])]" }

Thank you for this useful advise