Prevent specific field editing for specific users in ArcMap

Question

Hi, I have a task to lock fields editing for specific users. I started to check IEditEvents_Event with it's OnChangeFeature event, but I can't understand what exactly was changed and what was the original value. Also I failed all my attempts to undo changes. If I use IEditor.AbortOperation() it breaks ArcMap, if I use throw new COMException(msg, (int)0x80004005L) it does nothing.

As workaround for detecting field changes I came up with:
[PHP]
 private void FeatureChanged(IObject feature)
        {
            var editor = _editor as IEditor;

if (editor != null)
            {
                var workspaceEdit = (editor.EditWorkspace as IWorkspaceEdit2);
                var changes = workspaceEdit.get_EditDataChanges(esriEditDataChangesType.esriEditDataChangesWithinOperation);
                var classes = changes.ModifiedClasses;

var @class = classes.Next();

var cursor = changes.ExtractEx(@class, esriDifferenceType.esriDifferenceTypeUpdateNoChange);

// Prepare the output parameters.
                int featureID = -1;
                IRow sourceRow = null;
                IRow differenceRow = null;
                ILongArray fieldIndexes = null;

// Iterate through the cursor.
                cursor.Next(out featureID, out sourceRow, out differenceRow, out fieldIndexes);
                while (featureID != -1)
                {
                    for (int i = 0; i < fieldIndexes.Count; i++)
                    {
                        var index = fieldIndexes.get_Element(i);

if (index >= 3) // Stub
                        {

}
                    }

cursor.Next(out featureID, out sourceRow, out differenceRow, out fieldIndexes);
                }
            }
        }
[/PHP]

But the logic is very disgusting as I don't work with feature which came in handler.

So the question is - how to detect feature attribute changes for concrete columns, and undo it in some cases correctly?

DubravkoAntonic · Answer

No I don't know for this kind of event but you can listen OnSaveEdits and OnStopEditing to prevent saving edits to base.

DmitrySharov · Answer

Dubravko Antoni�?, thank you a lot. IRowChanges solved almost all my problems. Do you know if there is a good way of aborting edit operation or there is only a way of restoring field data?

DubravkoAntonic · Answer

Some kind of pseudo in some static part of extension preffetch all featureClass ObjectClassID that you need to filter public/private static List watchedFeatureClass = new List(); // for each FC you should add field indexes that you need to watch public/private Dictionary> watchedFields = new Dictionary>(); I rather prefer Object approach to create some class that will do this with some descriptive methods: private static List... private static Dictionary... public bool IsChanged(IFeature pFeature) public void RestoreOriginalValue() // in changed event IObject feature; IFeature pFeature = feature as IFeature; // use target ObjectClassID to determine if this is watched FC watchedFeatureClass .Contains(pFeature.Class.ObjectClassID) IRowChanges pRowChanges = pFeature as IRowChange; if(pRowChanges.ValueChanged) ... do some stuf like looping through Fields and test if http://resources.esri.com/help/9.3/ArcGISDesktop/ArcObjects/esrigeodatabase/IRowChanges_ValueChanged.htm I hope this hints will help. Or you can combine my method with yours.