ClassCast Exception when copying multi-user field from one issue to another

[Eva]

I am creating a postfunction plugin that copy a multi user value from one type of ticket to another ticket. I can copy the other fields fine, but when i copy anythign multi-select I get the following error:

[atlassian.jira.workflow.OSWorkflowManager] Caught exception while attempting to perform action 751 from workflow 18844 on issue 'TEST-3333'
java.lang.ClassCastException: java.util.ArrayList cannot be cast to com.opensymphony.user.User
at com.atlassian.jira.issue.customfields.impl.MultiUserCFType.getStringFromSingularObject(MultiUserCFType.java:152)

Here is my code:

final IssueChangeHolder changeHolder = new DefaultIssueChangeHolder();
    	ModifiedValue mv = null;	
    	ChangeItemBean bean = null;
    	FieldLayoutItem item = null;
    	CustomFieldType cfType = null;
    	Object oldValue = null;
    	Object newValue = null;
    	ArrayList<Object> changeItemBeans = null;
    	
    	//get custom fields that we need to copy over
    	List<CustomField> originalFields = Utilities.getCustomFields(newIssue);
    	issueToBe = issueManager.getIssueObject(oldIssue.getId()); //refresh this issue
        
    	//update the old ticket with each of the custom field that is in the included list
    	for (CustomField field : originalFields) {
			cfType = field.getCustomFieldType();
			
			oldValue = oldIssue.getCustomFieldValue(field);
			newValue = newIssue.getCustomFieldValue(field);
			if (newValue != null){
				mv = new ModifiedValue(oldValue, newValue);
				bean = new ChangeItemBean(ChangeItemBean.CUSTOM_FIELD,
						field.getName(),
						cfType.getStringFromSingularObject(oldValue),
						cfType.getStringFromSingularObject(oldValue),
						cfType.getStringFromSingularObject(newValue),
						cfType.getStringFromSingularObject(newValue));
				changeItemBeans = new ArrayList<Object>(); // clear the list
				changeItemBeans.add(bean);

				//make the change
				try {
					item = fieldLayoutManager.getFieldLayout(oldIssue).getFieldLayoutItem(field);
					field.updateValue(item, issueToBe, mv, changeHolder);
					issueToBe.setUpdated(UtilDateTime.nowTimestamp());
					issueToBe.store();
				} catch (FieldLayoutStorageException e) {
					log.warn(e.getMessage());
				}

				// now log the changes
				try {
					IssueUpdateBean issueUpdateBean = new IssueUpdateBean( issueToBe.getGenericValue(),
							oldIssue.getGenericValue(),EventType.ISSUE_UPDATED_ID, currUser);
					issueUpdateBean.setComment(changeHolder.getComment());
					issueUpdateBean.setChangeItems(changeItemBeans);
					issueUpdateBean.setDispatchEvent(true);
					issueUpdateBean.setParams(EasyMap.build("eventsource",
							IssueEventSource.ACTION));
					componentManager.getIssueUpdater().doUpdate(issueUpdateBean, true);
				} catch (JiraException e) {
					log.warn(e.getMessage());
				}
			}
        }

Any help is greatly appreciated!

[Dieter · Accepted solution]

Hi Eva,

The statement

oldValue = oldIssue.getCustomFieldValue(field);

will return a List of om.opensymphony.user.User objects if field is a MultiUserCFType. The method cfType.getStringFromSingularObject() does not work with lists as the name implies. So if oldvalue is a ist of User objects you should first convert that into something readable like a comma separated list of user names. I'd suggest to replace the the lines

cfType.getStringFromSingularObject(oldValue),
                cfType.getStringFromSingularObject(oldValue),
                cfType.getStringFromSingularObject(newValue),
                cfType.getStringFromSingularObject(newValue));

by

 makeString(oldValue,cfType),
 makeString(oldValue,cfType),
 makeString(newValue,cfType),
 makeString(newValue,cfType));

where makeString could look like:

private String makeString (Object value, CustomFieldType cfType) {
if (value instanceof List<User>) {
List<User> users = (List<User>)value;
StringBuilder sb = new StringBuilder();
for (User user: users) {
if (sb.length() > 0) {
sb.append(",");
}
sb.append(cfType.getStringFromSingularObject(user));
}
return sb.toString();
}
return cfType.getStringFromSingularObject(value);
}

[Dieter]

sorry for so many edits but i don't get the code formatting work anymore :(

[Dieter]

Yes, this should work since a multi-line free text field is not a List<User> and thus everything will fallback to your old code

[Eva]

What if the field is a Multi-line free text field? Would this sitll works?

[Eva]

Another quick question - What if I have other multi-values fields? Eclipse doesnt let me to do value instanceof List<Users>, it force me to use List<?>. And w/o knowing what type, I am not sure how to cast it. Any help is appreciated!

Thanks again!

[Dieter]

This is the more generic approach that also should handle other multi valued field

private String makeString(Object value, CustomFieldType cfType) {
if (value instanceof Collection<?>) {
Collection<?> objects = (Collection<?>) value;
StringBuilder sb = new StringBuilder();
for (Object object : objects) {
if (sb.length() > 0) {
sb.append(",");
}
sb.append(cfType.getStringFromSingularObject(object));
}
return sb.toString();
}
return cfType.getStringFromSingularObject(value);
}