How can i sum the same field on multiple task's onto another task's field?

[csordasmarci]

So let's say I have 3 tasks:

Test1
Test2
Sum

Whenever I edit the field "Cost" on a Test task I wan't my "Sum" field on the Sum task to be updated with all the Test task's "Cost" value summed up.

I don't mind if Test1 and Test2 has to be sub-tasks of Sum, if that makes it work.

So far this is my automation:

Trigger: When value changes for "Cost"

Action: Lookup work items? I think but here is where I get confused. Could anyone help me out?

[Tuncay Senturk · Accepted solution]

Hi @csordasmarci 

- trigger: field value changed (Cost)

- I'd also recommend adding a condition: issue type = sub-task , so that we'd ensure the rule only runs for sub-tasks.

- add a branch rule / related issues, type: parent

inside the branch

    - action: lookup issues

    - parent: {{issue.key}}

- edit issue (parent), field to update: Sum , value: {{lookupIssues.Cost.sum}}

I hope it's helpful