Need help combining and converting string values (stored as HH:mm:ss) with date value (yyyy-mm-dd)

Question

Need help combining and converting string values (stored as HH:mm:ss) with date value (yyyy-mm-dd)* I have a custom field (issue.customfield_11248) which is storing a string for time (StartTime). {format: string}
* I have another custom field (issue.customfield_11124) which is storing a the date (StartDate). {format: date}
* I have another two custom fields for EndTime and EndDate (issue.customfield_11250 and customfield_11125)
* The mask for entering data into the string field is HH:mm:ss

I need to calculate the days, hours, minutes and seconds between start date/time and end date/time, in a Jira Service Desk automation, and to populate that value into another customfield for "duration"As a first step I tried concatenating the time and date fields using:{{issue.customfield_11124.concat("T").concat(issue.customfield_11248)}}But this first step failed with:"Unable to render smart values when executing this rule:Too many numbers or variables: d h m s"I'm not a developer, and stumped how to progress... can anyone shed any light/insight?---Update: The field I was trying to populate (StartDateTime_GMT_Concatenated) with the concatenated values was of the incorrect type. This has been changed to a string value. While I can populate StartDateTime_GMT_Concatenated with two strings, i can't populate it with a date + string. So need to figure out how to convert issue.customfield_11124 into a string

Bill Sheboy · Answer

Thanks for that information, @Michael Catmur

Let's start with the most-likely possible causes...

Date value typing

You are concatenating a string to a date, and then trying to use that as a date / time.  Let's try helping the conversion a bit with forcing the first value explicitly to text before the concat() and then converting with a known format:

{{issue.customfield_11124.jiraDate.concat(" ").concat(issue.customfield_11248).toDate("yyyy-MM-dd HH:mm:ss")}}

Racetrack error

The Work Item Created trigger has a long-standing, racetrack timing problem. Specifically, the rule can start running before all of the data is available, or the item is even in a stable condition. This can appear as weird rule errors (e.g., permission problems, no issue type!, etc.) or conditions not matching as expected.

In the announcement for this advanced component feature, I asked the Atlassian team member about it and...they know about it, they are working on architectural changes to fix it, and there is no time frame for when this will be fixed.

Given that information, I have two recommendations:

* As other triggers can have this racetrack timing problem, perhaps do not use that new feature to add conditions to triggers yet. I advise this because the audit log does not show why a rule did not trigger with this new feature (yet). This will conceal any problems of a work item did not match the condition versus a timing problem.
* With the Work Item Created trigger, add the Re-fetch Work Item Data action immediately after the trigger, then followed by any conditions. This will slow the rule slightly, reloading the data before the steps proceed.

Please make those three changes and then retest your rule.  Thanks!

Michael Catmur_a8pn4v · Answer

moved on a little now.. have managed to get a custom field StartDateTime_Concatenated (issue.customfield_11578) as a string using:

{{issue.customfield_11124.format("yyyy-MM-dd").concat("T").concat(issue.customfield_11248).concat("Z")}}

this is storing values like "2025-08-21T10:10:10Z" in a string field.

Now i need to convert that ISO datetime  into a proper datetime value. I tried these: but get no value populated and no error message from the automation.

* {{issue.customfield_11578) | toDate}} and 
* {{issue.customfield_11578 | toDate("yyyy-MM-dd'T'HH:mm:ssZ")}}

Any suggestions?

Michael Catmur_a8pn4v · Answer

Thanks, for that. I tried it, but unfortunately get no extra info in the audit log