Make Field Optional Based on Behavior

[Kmmaughs]

I would like to make a field optional based on the selection of another field. 

I have ScriptRunner and was trying to use a Behavior. I have a multi-select drop-down field, and if an option is selected, then I want a drop-down field to become optional.

Here's the Behavior server-side script:

def multiSelectField = getFieldByName("My Multi-Select Field")
def  DropDown= getFieldByName("My Drop-Down Field")

def multiSelectvalue = multiSelectField.getValue()

if (multiSelectvalue.toString().contains("Option 3")) {
DropDown.setRequired(false) 
}else {
DropDown.setRequired(true)
}

When I go the Create screen and select Option 3 in my multiselect field, the drop-down field's required indicator does not change.

Any issues you see? What would another suggested approach be?

[Nic Brough -Adaptavist-]

Fields in Jira are made mandatory at the back-end first.   If you configure a field to be mandatory (by virtue of being one of certain system fields, or with a field configuration that tells the project it is mandatory), then you cannot turn that off by tinkering with it at the browser level, which is what Behaviours does.

So, you need to reverse the question.  It should be "use Behaviours to make a field mandatory when I need it to be"

[Kmmaughs]

I tried this in a way. My code looked like this:

def multiSelectField = getFieldByName("My Multi-Select Field")
def  DropDown= getFieldByName("My Drop-Down Field")

def multiSelectvalue = "Option 3" in multiSelectField*.value

if (!multiSelectvalue) {
DropDown.setRequired(true) 
}else {
DropDown.setRequired(false)
}

Another way I wrote it:

def multiSelectField = getFieldByName("My Multi-Select Field")
def  DropDown= getFieldByName("My Drop-Down Field")

if (! ('Option 3' in multiSelectField*.value)) {
DropDown.setRequired(true) 
}else {
DropDown.setRequired(false)
}

In either case, as I'm on the Create Issue screen, it starts out with the Drop Down required (as desired). However, when I select the value in the multi-select, the behavior doesn't change. If I reverse the setRequired settings, it shows the field as optional initially, as I would expect, so there isn't an overwriting field configuration. 

It just seems that when I select the value in the multi-select, perhaps it's not registering it to alter the field behaviour; I'm not sure.