How to get original Entity from ChangeTracker

.net c# entity-framework entity-framework-6


Is there a way to get the original Entity itself from the ChangeTracker (rather than just the original values)?

If the State is Modified, then I suppose I could do this:

// Get the DbEntityEntry from the DbContext.ChangeTracker...

// Store the current values
var currentValues = entry.CurrentValues.Clone();

// Set to the original values

// Now we have the original entity
Foo entity = (Foo)entry.Entity;

// Do something with it...

// Restore the current values

But this doesn't seem very nice, and I'm sure there are problems with it that I don't know about... Is there a better way?

I'm using Entity Framework 6.

2/21/2013 9:31:49 PM

Accepted Answer

Override SaveChanges of DbContext or just access ChangeTracker from the context:

foreach (var entry in context.ChangeTracker.Entries<Foo>())
    if (entry.State == System.Data.EntityState.Modified)
        // use entry.OriginalValues
        Foo originalFoo = CreateWithValues<Foo>(entry.OriginalValues);

Here is a method which will create a new entity with the original values. Thus all entities should have a parameterless public constructor, you can simply construct an instance with new:

private T CreateWithValues<T>(DbPropertyValues values)
    where T : new()
    T entity = new T();
    Type type = typeof(T);

    foreach (var name in values.PropertyNames)
        var property = type.GetProperty(name);
        property.SetValue(entity, values.GetValue<object>(name));

    return entity;
4/20/2017 8:53:14 PM

Popular Answer

Nice. Here is a slightly modified version that will handle complex properties:

public static TEntity GetOriginal<TEntity>(this DbContext ctx, TEntity updatedEntity) where TEntity : class
        Func<DbPropertyValues, Type, object> getOriginal = null;
        getOriginal = (originalValues, type) =>
                 object original = Activator.CreateInstance(type, true);
                 foreach (var ptyName in originalValues.PropertyNames)
                     var property = type.GetProperty(ptyName);
                     object value = originalValues[ptyName];
                     if (value is DbPropertyValues) //nested complex object
                         property.SetValue(original, getOriginal(value as DbPropertyValues, property.PropertyType));
                         property.SetValue(original, value);
                 return original;
        return (TEntity)getOriginal(ctx.Entry(updatedEntity).OriginalValues, typeof(TEntity));

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