Unsupported JSON character in JSONPath starting with ...

[hozzer]

Hi,

I'm using Zabbix Server 4.2.3 and have been following this doc, https://www.zabbix.com/documentation...items/jsonpath.

I have copied the JSON input data and inserted into a Value for Test Item preprocessing.

I then run some tests in which the JSONPath Parameters match up with the examples toward the bottom of the same doc mentioned above.

Out of all the examples given, only the following work as intended and return a result:

$.filters.price
$.filters.category
$.filters['no filters']
$.filters
$.books[1].title


ALL others result in unsupported errors, two examples:

cannot extract value from json by path "$.books[-1].author": unsupported character in json path starting with: "[-1].author"
cannot extract value from json by path "$.services[?(@.active==“false”)].servicegroup": unsupported character in json path starting with: "[?(@.active==“false”)].servicegroup"


Does anyone have any troubleshooting advice?

[gofree]

Try replace " with ' in active == 'false '

[hozzer]

Thanks for you response but unfortunately I can still see the error:
cannot extract value from json by path "$.services[?(@.active=='false')].servicegroup": object not found starting with json path: "services[?(@.active=='false')].servicegroup"
cannot extract value from json by path "$.services[?(@.active == 'false')].servicegroup": object not found starting with json path: "services[?(@.active == 'false')].servicegroup"

This also does not explain why the simpler $.books[-1].author parameter is not supported.

[gofree]

work in mine no issue , try to upgrade to 4.2.6 just in case there has been some bug in 4.2.3

more likely you didnt copy it properly ( json data ) - double check

[chojin]

I see the same kind of behaviour:
I have a master item that gets item data like this:

{"strings":["AutoFullBackup-20190912_160006","AutoFullBackup-20190913_160125","AutoFullBackup-20190914_160232","AutoFullBackup-20190915_160343","AutoFullBackup-20190916_160453","AutoFullBackup-20190917_160606","AutoFullBackup-20190918_160716","AutoFullBackup-20190919_160835","AutoFullBackup-20190920_161000","AutoFullBackup-20190921_161111","AutoFullBackup-20190922_161219","AutoFullBackup-20190924_140600","AutoFullBackup-20190925_140714","AutoFullBackup-20190926_140825","AutoFullBackup-20190927_140940","AutoFullBackup-20190928_141050","AutoFullBackup-20190929_141200","AutoFullBackup-20190930_141312","AutoFullBackup-20191001_141426","AutoFullBackup-20191002_141541","AutoFullBackup-20191003_141651"]}

Then I have 2 dependent items which turn to unsupported with an error:

• Item: Number of backups
  Preprocessing: JSONPath: $.strings.length()
  Error:
  Preprocessing failed for: {"strings":["AutoFullBackup-20190912_160006","AutoFullBackup-20190913_160125","AutoFullBackup-201...
  1. Failed: cannot extract value from json by path "$.strings.length()": object not found starting with json path: "length()"
• Item: Last backup
  Preprocessing: JSONPath: $.strings[-1]
  Error:
  Preprocessing failed for: {"strings":["AutoFullBackup-20190912_160006","AutoFullBackup-20190913_160125","AutoFullBackup-201...
  1. Failed: cannot extract value from json by path "$.strings[-1]": unsupported character in json path starting with: "[-1]"

When I copy-paste the data from the master item into the Preprocessing test dialog of the UI.. I do get the expected results:
For Item 1 I get "21" as test result
and for item 2 I get "AutoFullBackup-20191003_141651" as test result

So why are those items turning unsupported with errors which suggest that json path does not understand the function length() and instead tries to find a key "length()" and that it does not seems to understand negative array indexes ?

I have read the documentation many times to check if I make some stupid mistake.. but I don't see the problem..
Also the tests using the UI turn out exactly as expected..
Is JSONpath in zabbix server partly broken ?
(Running version 2.4.7)

As the JSON test vs the actual result give totally different values, I opened a bug: https://support.zabbix.com/browse/ZBX-16727

[chojin]

It seems my problem was caused by a <4.2.5 zabbix proxy, not yet supporting those jsonpath notations. Upgrading the proxy, or monitoring those items without proxy, solved the problem.

The tester in the web UI uses the server to test the item hence the correct evalutation. But the actual preprocessing of the items is done by the proxy itself.