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    <p>Very, very rough idea:</p> <pre><code>foreach (var property in dbEntityEntry.Entity.GetType().GetProperties()) { DbPropertyEntry propertyEntry = dbEntityEntry.Property(property.Name); if (propertyEntry.IsModified) { Log.WriteAudit("Entry: {0} Original :{1} New: {2}", property.Name, propertyEntry.OriginalValue, propertyEntry.CurrentValue); } } </code></pre> <p>I have no clue if this would really work in detail, but this is something I would try as a first step. Of course there could be more then one property which has changed, therefore the loop and perhaps multiple calls of <code>WriteAudit</code>.</p> <p>The reflection stuff inside of SaveChanges could become a performance nightmare though.</p> <p><strong>Edit</strong></p> <p>Perhaps it is better to access the underlying <code>ObjectContext</code>. Then something like this is possible:</p> <pre><code>public class TestContext : DbContext { public override int SaveChanges() { ChangeTracker.DetectChanges(); // Important! ObjectContext ctx = ((IObjectContextAdapter)this).ObjectContext; List&lt;ObjectStateEntry&gt; objectStateEntryList = ctx.ObjectStateManager.GetObjectStateEntries(EntityState.Added | EntityState.Modified | EntityState.Deleted) .ToList(); foreach (ObjectStateEntry entry in objectStateEntryList) { if (!entry.IsRelationship) { switch (entry.State) { case EntityState.Added: // write log... break; case EntityState.Deleted: // write log... break; case EntityState.Modified: { foreach (string propertyName in entry.GetModifiedProperties()) { DbDataRecord original = entry.OriginalValues; string oldValue = original.GetValue( original.GetOrdinal(propertyName)) .ToString(); CurrentValueRecord current = entry.CurrentValues; string newValue = current.GetValue( current.GetOrdinal(propertyName)) .ToString(); if (oldValue != newValue) // probably not necessary { Log.WriteAudit( "Entry: {0} Original :{1} New: {2}", entry.Entity.GetType().Name, oldValue, newValue); } } break; } } } } return base.SaveChanges(); } } </code></pre> <p>I've used this myself in EF 4.0. I cannot find a corresponding method to <code>GetModifiedProperties</code> (which is the key to avoid the reflection code) in the <code>DbContext</code> API.</p> <p><strong>Edit 2</strong></p> <p><strong>Important</strong>: When working with POCO entities the code above needs to call <code>DbContext.ChangeTracker.DetectChanges()</code> at the beginning. The reason is that <code>base.SaveChanges</code> is called too late here (at the end of the method). <code>base.SaveChanges</code> calls <code>DetectChanges</code> internally, but because we want to analyze and log the changes before, we must call <code>DetectChanges</code> manually so that EF can find all modified properties and set the states in the change tracker correctly.</p> <p>There are possible situations where the code can work without calling <code>DetectChanges</code>, for example if DbContext/DbSet methods like <code>Add</code> or <code>Remove</code> are used after the last property modifications are made since these methods also call <code>DetectChanges</code> internally. But if for instance an entity is just loaded from DB, a few properties are changed and then this derived <code>SaveChanges</code> is called, automatic change detection would not happen before <code>base.SaveChanges</code>, finally resulting in missing log entries for modified properties.</p> <p>I've updated the code above accordingly.</p>
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    1. POEntity Framework 4.1 DbContext Override SaveChanges to Audit Property Change
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    1. POEntity Framework 4.1 DbContext Override SaveChanges to Audit Property Change
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    1. COThis works, but it seems that all properties are modified according to this. Will investigate further, but fine for original question. I think this gives me what I need.
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      1. USJames Pogran
    2. COThis does not work for me. The old values are always empty. Is this working only for POCO and 4.1 and up?
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    3. CO@Jonx: Yes, it's EF 4.1 (`DbContext`) and POCO. You can do something similar though for <= EF 4.0 (`ObjectContext`), the only difference is that you don't overwrite `SaveChanges` but implement an event handler (`OnSavingChanges` or similar, I don't remember exactly).
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