Understanding the ValueGeneratedOnAdd feature

Steps to reproduce

I am trying to build an example of .ValueGeneratedOnAdd() and .ValueGeneratedOnAddOrUpdate() for a book. The .ValueGeneratedOnAddOrUpdate() property doesn’t seem to be updated.

The issue

Summary: I have a CreatedOn property with the .ValueGeneratedOnAdd() setting and UpdatedOn property with the .ValueGeneratedOnAddOrUpdate() setting. If I create an entry, wait a second, and update that entry the UpdatedOn is not updated. I also notice the SQL database column UpdatedOn isn’t changing.

I assume I have the setup wrong, but I don’t see where. You input would be appreciated.

My DbContext is:

public class EfCoreContext : DbContext             
{
    public DbSet<BookAndAuthor> 
        BookAndAuthors { get; set; }               

    public EfCoreContext(
        DbContextOptions<EfCoreContext> options)   
        : base(options)
    { }

    protected override void 
        OnModelCreating(ModelBuilder modelBuilder) 
    {
        modelBuilder.Entity<BookAndAuthor>()
            .Property(x => x.CreatedOn)
            .HasDefaultValueSql("getutcdate()")
            .ValueGeneratedOnAdd();

        modelBuilder.Entity<BookAndAuthor>()
            .Property(x => x.UpdatedOn)
            .HasDefaultValueSql("getutcdate()")
            .ValueGeneratedOnAddOrUpdate();

        ...//setting for other properties left out
        base.OnModelCreating(modelBuilder);
    }
}

My class is:

public class BookAndAuthor
{
    public int BookAndAuthorId { get; set; }  
    public DateTime CreatedOn { get; set; }
    public DateTime UpdatedOn { get; set; }
   ... //other properties removed     
}

My Unit Test is:

[Fact]
public void TestDefaultValueAddOrUpdateOk()
{
    //SETUP
    var connection = this.GetUniqueDatabaseConnectionString();
    var optionsBuilder =
        new DbContextOptionsBuilder<EfCoreContext>();

    optionsBuilder.UseSqlServer(connection);
    var options = optionsBuilder.Options;

    using (var db = new EfCoreContext(options))
    {
        db.Database.EnsureCreated();
        var books = EfTestData.CreateFourBooks();
        db.BookAndAuthors.AddRange(books);
        db.SaveChanges();
        Thread.Sleep(1000);

        //ATTEMPT 
        var firstBook = books.First();
        firstBook.Description = $"has changed on {DateTime.UtcNow:u}";
        db.SaveChanges();

        //VERIFY                                    
        firstBook.UpdatedOn.ShouldNotEqual(firstBook.CreatedOn);
    }
}

The test fails, as the UpdatedOn is the same as the CreatedOn value. Looking at the time in the description the UpdatedOn value has not been updated.

If you are seeing an exception, include the full exceptions details (message and stack trace). n/a

Further technical details

EF Core version: “Microsoft.EntityFrameworkCore.SqlServer”: “1.1.0-preview1-final”, Operating system: Windows 10 Visual Studio version: Microsoft Visual Studio Professional 2015 Version 14.0.25425.01 Update 3 Microsoft .NET Framework Version 4.6.01586

Other details about my project setup: Pretty normal setup.