Change the storeConfig
to keep the records from trying to update after being grouped:
storeConfig : {
remoteSort : false,
remoteGroup : false,
remoteFilter : false,
}
Add a listener to the load
event which assigns a root level property to the record and groups by that record value. (For some reason store.group('Parent.Name');
doesn't work.)
load: function(store) {
store.each(function(record) {
record.set('ParentName', record.get('Parent') && record.get('Parent').Name || '-- Unparented --');
});
store.group('ParentName');
}