How to display process variable in a Form

Hi,

I have defined a process variable with an generated string uid as content.

I'm currently not able to display it and either the list of process variable.

I access variable through the bpm API via

  1. ../API/bpm/caseVariable/?p=0&c=10&f=case_id={{caseId}} for the list of variables
  2. ../API/bpm/caseVariable/{{caseId}}/extractionKey  for the specific variable extractionKey

Although i can access them via urls

localhost:8080/bonita/API/bpm/caseVariable/27050/extractionKey

localhost:8080/bonita/API/bpm/caseVariable/p=0&c=10&f=case_id=27050.

I'm not able to display extractionKey.value , it seems to be empty.

I'm either not able to display the table which should content all the variables of the process 

I'm using the latest version 2022.1

The only thing I may think of is the following stacktrace

java.lang.NumberFormatException: null
    at java.lang.Long.parseLong(Long.java:655) ~[?:?]
    at java.lang.Long.valueOf(Long.java:1144) ~[?:?]
    at org.bonitasoft.web.rest.server.api.bpm.cases.APICaseVariable.runSearch(APICaseVariable.java:56) ~[console-server-7.14.0.jar:?]
    at org.bonitasoft.web.rest.server.framework.APIServletCall.doGet(APIServletCall.java:172) ~[console-server-7.14.0.jar:?]  

But , i don't understand because there isn't a Long process variable in the whole process

Thx

After thinking a bit and making some experience . I think that is due to the visibility of process's variables.

In my use case , i have 3 pools with 3 different processes:

1) data generation 

2) segmentation 

3) multiple form generation from 2)

In process 1) i assign the general extraction key process variable that i want to reuse for each form generation at process 3.

Is it possible that I can't have visibility on this extraction key from process 3?

An other issue is even I redefine for each process a process variable like extractionKey,extractionKey2,extractionKey3 (with different name corresponding to be safe) , it seems that I can't only access to the variables defines in the first process (DataGeneration) which is the initiator process associated with the case, which is the only process I see in the administration console cases list.

It seems that i should use Business Data to access cross processes, right?
Isn't a way from forms to access underlining process variables?