Error: Find criteria must contain at least one sort field value.

Question

Hi
I am getting the followng error in Sort.as when I click on a column in a DataGrid that is bound to a nested property (e.g. parent.name)
Error: Find criteria must contain at least one sort field value.
I can see why this is failing.
In the findItem function of Sort.as the code tests whether there is data in line (456) hasFieldName = values[fieldName] !== undefined. This fails and so an error is raised later in the function by:
     if (fieldsForCompare.length == 0)     {
     message = resourceManager.getString("collections", "findRestriction"); 
          throw new SortError(message);     }
 The code needs to traverse down the object hierarchy to get the field so that error is not thrown .
The code needs to traverse down the object hierarchy to get the field so that error is not thrown .
In the case of a non nested property, everything works fine.
There is lots of discussion about nested properties in DataGrid and there is this jira:
http://bugs.adobe.com/jira/browse/SDK-9801
There is talk of using a labelFunction or an itemRenderer and other third party solutions (extensions of DataGridColumn).
Is this a bug?  is there a workaround using labelFunction or itemRenderer which can stop the error in Sort.as?
James
Here is the code of findItem in Sort.as of SDK 3..4.0.9271
public  
function findItem(items:Array,values:Object,
mode:String,
returnInsertionIndex:Boolean =
false,compareFunction:Function =
null):int{
var compareForFind:Function; 
var fieldsForCompare:Array; 
var message:String; 
if (!items){
message = resourceManager.getString(
"collections", "noItems"); 
throw new SortError(message);}
else if (items.length == 0){
return returnInsertionIndex ? 1 : -1;}
if (compareFunction == null){
compareForFind =
this.compareFunction; 
// configure the search criteria
if (values && fieldList.length > 0){
fieldsForCompare = [];
//build up the fields we can compare, if we skip a field in the
//middle throw an error. it is ok to not have all the fields
//though
var fieldName:String; 
var hadPreviousFieldName:Boolean = true; 
for (var i:int = 0; i < fieldList.length; i++){
fieldName = fieldList[i];
if (fieldName){
var hasFieldName:Boolean; 
try
hasFieldName = values[fieldName] !==
undefined;}
catch(e:Error){
hasFieldName =
false;}
if (hasFieldName){
if (!hadPreviousFieldName){
message = resourceManager.getString(
"collections", "findCondition", [ fieldName ]); 
throw new SortError(message);}
else
fieldsForCompare.push(fieldName);
else
hadPreviousFieldName =
false;}
else
//this is ok because sometimes a sortfield might
//have a custom comparator
fieldsForCompare.push(
null);}
if (fieldsForCompare.length == 0){
message = resourceManager.getString(
"collections", "findRestriction"); 
throw new SortError(message);}
else
try
initSortFields(items[0]);
catch(initSortError:SortError){
//oh well, use the default comparators...
else
compareForFind = compareFunction;

Answer 1

I have tried a sortCompareFunction:
var sort:Sort = new Sort();
sort.compareFunction = compareFunction;sort.fields = [sortField];
data.sort = sort;
data.refresh();
this makes no difference.
James