Created and Modified date issue - asp.net

Question

I was practicing User.Identity and timestamps functions in ASP.NET MVC 5,
So I created a student class filled some properties, I just wanted to test if it is capturing timestamps and userId, so user id is getting captured and datetime too, problem is whenever I'm editing a record and save it, its created date becomes Null and modified date is updated, please review the code and help.
Thanks in advance.
Below is the Code
{
public class BaseEntity
{
public DateTime? DateCreated { get; set; }
public string UserCreated { get; set; }
public DateTime? DateModified { get; set; }
public string UserModified { get; set; }
}
public class Student : BaseEntity
{
public int Id { get; set; }
public string Name { get; set; }
public string Subject { get; set; }
public string Class { get; set; }
public Section Section { get; set; }
public byte SectionId { get; set; }
}
then I used Codefirst approach and created an application Database and added this code in Identity Model
public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
public DbSet<Student> Students { get; set; }
public override int SaveChanges()
{
AddTimestamps();
return base.SaveChanges();
}
//public override async Task<int> SaveChangesAsync()
//{
// AddTimestamps();
// return await base.SaveChangesAsync();
//}
private void AddTimestamps()
{
var entities = ChangeTracker.Entries().Where(x => x.Entity is BaseEntity && (x.State == EntityState.Added || x.State == EntityState.Modified));
var currentUsername = !string.IsNullOrEmpty(System.Web.HttpContext.Current?.User?.Identity?.Name)
? HttpContext.Current.User.Identity.Name
: "Anonymous";
foreach (var entity in entities)
{
if (entity.State == EntityState.Added)
{
((BaseEntity)entity.Entity).DateCreated = DateTime.UtcNow;
((BaseEntity)entity.Entity).UserCreated = currentUsername;
}
else
((BaseEntity)entity.Entity).DateModified = DateTime.UtcNow;
((BaseEntity)entity.Entity).UserModified = currentUsername;
}
}
public DbSet<Section> Sections { get; set; }
public ApplicationDbContext()
: base("DefaultConnection", throwIfV1Schema: false)
{
}
public static ApplicationDbContext Create()
{
return new ApplicationDbContext();
}
}
I have created a simple controller with create,edit and dispay actions.

Answer 1

The code you posted doesn't show DateCreated being set to null as far as I can see. I think the issue is when you save an existing record you do not have the DateCreated or UserCreated fields in your view. So when you post the form the MVC model binder doesn't see them and thus sets them to null (I'm assuming your are binding to the Student model in your controller action).
In your edit view add the following hidden fields:
#Html.HiddenFor(model => model.DateCreated)
#Html.HiddenFor(model => model.UserCreated)
Now when you post the form the MVC model binder will bind these values to your model and save them to the database.