Support parameters and/or parent/root level objects

[jingkunhub]

I’m expecting a feature of supporting parameters assigned with internal or external json fragments in the same way as in XSLT. One of the use cases is to use such parameterized objects inside #loop. Or it’ll service the same purpose if providing a mechanism to access root/parent level fragments.

I am not able to find similar functionality in the current code base.

[Courela]

There's an alias called 'root' for accessing properties from root element/input, if that's what you want. That feature is not documented though...

PS: #valueof path was always an absolute path, $ was a reference to input's root, I don't recall if it still behaves that way...

[jingkunhub]

Great! I will try what you suggested and reply with my results ASAP.

[jingkunhub]

Hi Courela,

Just confirmed that #valueof path always the absolute one. This is exactly what I need for now.

Also, I tried $ reference to the input root, with $, $. #valueof($). All of them gave me the null output. What's the exact usage?

Thanks,
Jingkun

[Courela]

Dollar sign refers to the root/start of the element being processed, as described in JsonPath. For #valueof function, it's always the whole input, but if you're in a loop, every other function will reference the element being processed, if no alias is specified. If you want to refer to a property/element outside the loop, you can use alias, being 'root' a special alias that references whole input.

Usually, the transformation returns null if there's an error, one can change that creating a transformer using EvaluationMode.Strict

new JsonTransformer(new JUSTContext { EvaluationMode = EvaluationMode.Strict })

[jingkunhub]

Hi Courela,

Than you very much for your suggestion. using EvaluationMode.Strict just help me identified the root cause of an issue - only an actual value allowed in the following condition where I'm trying to compare a value from #valueof or #currentvalueatpath,

Input:
{ "open": "open", "close": "close", "menu": { "popup": { "menuitem": [ { "value": "Open", "onclick": "OpenDoc()" }, { "value": "Close", "onclick": "CloseDoc()" } ], "submenuitem": "CloseSession()" } } }

Transformer:
{ "result": { "Open": "#valueof($.menu.popup.menuitem[?(@.value == #valueof($.open)].onclick)", "Close": "#valueof($.menu.popup.menuitem[?(@.value == #valueof($.close))].onclick)" } }
The error is 'Error while calling function : #valueof($.menu.popup.menuitem[?(@.value == #valueof($.open)].onclick) - Unexpected character while parsing path query: #

I used the first example of valueof to illustrate my use case of feeding #valueof as the 2nd comparator.

How to handle dynamic values in the above sample?

Thanks,
Jingkun

[Courela]

You have to use #concat/#xconcat to make a dynamyc expression/path to #valueof

{ "result": { "Open": "#valueof(#xconcat($.menu.popup.menuitem[?/(@.value == ',#valueof($.open),'/)].onclick))", "Close": "#valueof(#xconcat($.menu.popup.menuitem[?/(@.value == ',#valueof($.close),'/)].onclick))" } }

Note that you have to escape parenthesis inside the dynamic expression, or they will be considered as a function open/close instead of a character of a string

.menuitem[?/(@.value

Two notes:

• since you are comparing strings on JsonPath filter, you need to include apostrophe (') around the value
• in your input, values of "open" and "close" start with lowercase, so they won't match the JsonPath filter