Undo changes in entity framework entities

Question

this might be a trivial question but: Since ADO.NET entity framework automatically tracks changes (in generated entities) and therefore keeps the original values, how can I rollback changes made to the entity objects?

I have a form which allows the user to edit a set of "Customer" entities in a grid view.

Now I have two buttons "Accept" and "Revert": if "Accept" is clicked, I call Context.SaveChanges() and the changed objects are written back to the database. If "Revert" is clicked, I would like for all objects to get their original property values. What would be the code for that?

Thanks

Answer 1

Query ChangeTracker of DbContext for dirty items. Set deleted items state to unchanged and added items to detached. For modified items, use original values and set current values of the entry. Finally set state of modified entry to unchanged:

public void RollBack()
{
    var context = DataContextFactory.GetDataContext();
    var changedEntries = context.ChangeTracker.Entries()
        .Where(x => x.State != EntityState.Unchanged).ToList();

    foreach (var entry in changedEntries)
    {
        switch(entry.State)
        {
            case EntityState.Modified:
                entry.CurrentValues.SetValues(entry.OriginalValues);
                entry.State = EntityState.Unchanged;
                break;
            case EntityState.Added:
                entry.State = EntityState.Detached;
                break;
            case EntityState.Deleted:
                entry.State = EntityState.Unchanged;
                break;
        }
    }
 }