Sum Of Two Calculation field to third custom field

[SHANAVASH MOHAMED]

Hi,

I want to display sum of two number fields to third number field.

E.g. 

Two Subtasks (Child issue )and One Story (Parent Issue)

Subtask 1 : custom field value 10

Subtask 2 : custom field value 20

If i closed two subtask then sum the both filed value to third custom field 

Story : Custom field : 30

the Third custom field in parent issue : e.g (Story,epic)

Can you please suggest how to get this via Workflow transition / using power script

[Alexander Pappert]

Where do you want the 3rd field?

If it is in Subtask, you could work with JMCF

something like

(issue.get("customfield_1") != null ? issue.get("customfield_1") : 0) + (issue.getParentObject("customfield_2") != null ? issue.getParentObject("customfield_2") : 0)

Or Automation for jira with the math operation

maybe you have to copy the values from subtask to parent first before you can calculate them

[SHANAVASH MOHAMED]

3rd custom field be story issue type