[Isomorphic]

BTW I was not able to use DSRequest.parentNode. It appeared to be null in most cases.

It's present when fetching children only.

Suggestion for a possible enhancement? ... perhaps a feature that allows specifying certain non-primary-key fields that must be provided along with primary-key values in data source requests

The combination of dsRequest.oldValues and dsRequest.parentNode would seem to cover this already, for all scenarios.

[bbruyn]

It's not the use case described here, exactly, but I found that I was able to edit/update a primary key by using the addRelatedUpdates approach outlined earlier. For what it's worth, with the sample 'employees' datasource and a 10/26 4.1d Power build:

    public void onModuleLoad() {

    	TreeGrid grid = new TreeGrid();
    	DataSource ds = DataSource.get("employees");
    	
    	grid.setWidth(400);
    	grid.setHeight(800);
    	grid.setCanEdit(true);
    	grid.setAutoFetchData(true);

    	grid.setDataSource(ds);
    	grid.setUpdateOperation("updatePrimaryKey");
    	grid.setFields(new ListGridField("Name"), new ListGridField("EmployeeId"));
    	
    	VLayout layout = new VLayout();
    	layout.addMember(grid);
    	
    	layout.draw();
    }

public class UpdatePrimaryKey {

	private static Logger log = new Logger(UpdatePrimaryKey.class);
	
	public DSResponse update(DSRequest request) throws Exception {

		DataSource ds = request.getRPCManager().getDataSource(request.getDataSourceName());

		Object oldKey = null;
		Map<String, Object> oldValuesMap = request.getOldValues();
		if (oldValuesMap != null) {
			oldKey = oldValuesMap.get("EmployeeId");
		}
		
		Object key = request.getFieldValue("EmployeeId");
		if (oldKey == null || oldKey.equals(key)) {
			return request.execute();
		}

		//first update the record as if the key were not being changed
		request.setCriteria("EmployeeId", oldKey);
		request.setFieldValue("EmployeeId", oldKey);
		
		DSResponse response = request.execute();

		//then delete the row
		DSRequest delete = new DSRequest(ds.getName(), DataSource.OP_REMOVE, request.getRPCManager());
		delete.setCriteria("EmployeeId", oldKey);
		DSResponse deleted = delete.execute();

		//and add the complete record, as returned by request.execute, back with the new key 
		DSRequest add = new DSRequest(ds.getName(), DataSource.OP_ADD, request.getRPCManager());
		add.setValues(response.getDataMap());
		add.setFieldValue("EmployeeId", key);		
		DSResponse added = add.execute();
		
		//finally, update any related nodes to take the new key
		DSRequest update = new DSRequest(ds.getName(), DataSource.OP_UPDATE, request.getRPCManager());
		update.setAllowMultiUpdate(true);
		update.setCriteria("ReportsTo", oldKey);
		update.setFieldValue("ReportsTo", key);
		DSResponse updated = update.execute();
		
		//include the value of the record as it was before it was updated, so the client can match one last time for cache sync
		response.setFieldValue("EmployeeId", oldKey);
		
		//and let it know about the fresh record we replaced it with
		response.addRelatedUpdate(added);
		response.addRelatedUpdate(deleted);
		
		if (updated.getAffectedRows() > 0) {
			response.addRelatedUpdate(updated);				
		}
		
		return response;
		
	}
}