EntityFramework Core: Get changes occured in entity and related data

Question

I want to get changes occured in an entity and related datas attached to it.

I know how to get the property names that have changed in one entity:

 dbContext.Entry(entity).Properties.Where(x => x.IsModified).Select(x => x.Metadata.Name).ToList();

How to do the same for related data in navigation properties ?

Answer 1

Based on this article (Entity Change Tracking using DbContext in Entity Framework 6), you should override SaveChanges() method to track entity changes and its related entities.

public override int SaveChanges()
{
    return base.SaveChanges();
} 

Actually, You should change the above code to the following sample:

public override int SaveChanges()
{
    var modifiedEntities = ChangeTracker.Entries()
        .Where(p => p.State == EntityState.Modified).ToList();
    var now = DateTime.UtcNow;

    foreach (var change in modifiedEntities)
    {
        var entityName = change.Entity.GetType().Name;
        var primaryKey = GetPrimaryKeyValue(change);

        foreach(var prop in change.OriginalValues.PropertyNames)
        {
            var originalValue = change.OriginalValues[prop].ToString();
            var currentValue = change.CurrentValues[prop].ToString();
            if (originalValue != currentValue) //Only create a log if the value changes
            {
                //Create the Change Log
            }
        }
    }
    return base.SaveChanges();
}