CODEWITHSUNDEEP
entity-frameworkentity-framework-4.1audit-trail
VAAA
VAAA

Reputation: 15039

EF 6 OriginalValues lost when using Attach method

I have the following Update generic method for my entities:

public void Update < T > (T entity) where T: class {
    DbEntityEntry dbEntityEntry = DbContext.Entry(entity);
    if (dbEntityEntry.State == System.Data.Entity.EntityState.Detached) {

        DbContext.Set < T > ().Attach(entity);

    }
    dbEntityEntry.State = System.Data.Entity.EntityState.Modified;
}

After SaveChanges() the data is successfully updated in the DB.

Now I nee to implement and Audit Log before SaveChanges() but I noticed that CurrentValues are equal to OriginalValues:

// For updates, we only want to capture the columns that actually changed
if (!object.Equals(dbEntry.OriginalValues.GetValue<object>(propertyName), dbEntry.CurrentValues.GetValue<object>(propertyName))){

  //here I add a new Audit Log entity

}

Any clue on how to solve this? Or is there a better way to do it in Entity Framework 6?

Upvotes: 2

Views: 1594

Answers (2)

Orestes G.
Orestes G.

Reputation: 61

If you are using a disconnected entity, you can set originals values without affect entity instance values, adapt this method at you needs

public static void LoadOriginalValues(this WorkflowsContext db, DbEntityEntry entity) 
        {
            var props = entity.GetDatabaseValues();

            foreach (var p in props.PropertyNames)
            {
                if (entity.Property(p).IsModified)
                {
                    entity.Property(p).OriginalValue = props[p];
                }
            }
        }

Upvotes: 2

JotaBe
JotaBe

Reputation: 39025

The original values are recovered from the entity itself. If the entity is being tracked by a context, this information is available.

In your case, you're using a disconected entity, so there is no change tracking, and the entity doesn't have the original values.

SO, in this case, if you need the original values there is no other option than getting them from the DB, and compare them, one by one.

If you want to get an entity that behaves as if it had been tracked by the context you can use a context to read the entity from the DB, and use something like ValueInjecter to automatically set the property values from the disconected entity into the tracked entity.

Upvotes: 1

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