I spend a fair amount of time writing listeners with ScriptRunner, so that Jira will do various things for me based on certain criteria. For example, I write a lot of listeners that listen for when an issue is updated, and take action accordingly.

Until today, however, I had never thought how I might leverage the system to determine what kind of update had triggered the event.  I always just wrote the criteria in by hand, so that the listener would ignore anything I didn’t want eliciting a reaction.

The listener I was working on today got so complex, had so many nested IF statements and conditions, that it occurred to me to search for a better way.

As it turns out, the event object contains a lot of information, including which field’s change triggered the listener.  

In my own example, I was looking at the labels field.  I wanted the script to send a Slack message if the issue had been updated, but only if the labels had changed in a certain way.

The line of code required to check the type of update event doesn’t even require an import:

def change = event?.getChangeLog()?.getRelated("ChildChangeItem")?.find {it.field == "labels"}

if (change) {
//Do something
}else{
/Do something else
}

The code is pretty simple, and comes courtesy of an answer on the Atlassian customer forums.   Change is defined as an object that exists if the event change log contains the label field.  If the change log contains the label field, then that field was at least one of the fields that was updated to trigger the update event.

With this, I was able to greatly simplify the code required to ensure that the listener was reacting appropriately.  It’s a small thing, but it makes a big change!