What script can I use to restrict the values on a cascade select field?

[Julia]

I have a Cascade Select custom field with the id "19000" and want to restrict the visible values depending on the issue type selected. 

I cannot figure out which script to use... any help would be appreciated 

[Peter-Dave Sheehan]

This should be a good place to start: https://library.adaptavist.com/entity/dynamic-select

Of course, this is for basing one single select on another, not adjusting the list in a cascading select. But it's virtually the same.

Here is a sample script:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.customfields.option.Option
def optionsManager = ComponentAccessor.optionsManager

def csFieldName = 'Root Cause'
def csFieldId   = 'customfield_19000'
def csFormField = getFieldByName(csFieldName) // or getFieldById(csFieldId)

def issueType   = issueContext.issueType.name
def issueTypeOptionMap = [
   IssueType1:['Option1', 'Option2'], 
   IssueType2:['Option3', 'Option4']
]


def allowedOptionsValues = issueTypeOptionMap[issueType]
if(allowedOptionsValues){
    def csCf = ComponentAccessor.customFieldManager.getCustomFieldObject(csFormField.fieldId)
    def config = csCf.getRelevantConfig(issueContext)
    def options = optionsManager.getOptions(config)

    Map allowedOptions = options.findAll{it.value in allowedOptionsValues}.inject(["":'None']){ Map map, Option opt-> 
        map[opt.optionId as String] = opt.value
        map
    }
    csFormField.setFieldOptions(allowedOptions)
} else {
    csFormField.setHelpText("No valid options for this issue type:$issueType")
}