Accessing HttpContext.Current.User.Identity.Name in the DbContext

Question

I'm going to use the UserName for tracking Created and Modified fields. To do that I have referenced to the System.Web assembly directly inside DbContext:

public void auditFields()
 {
            var auditDate = DateTime.Now;
            foreach (var entry in this.ChangeTracker.Entries<BaseEntity>())
            {
                switch (entry.State)
                {
                    case EntityState.Detached:
                        break;
                    case EntityState.Unchanged:
                        break;
                    case EntityState.Added:
                        entry.Entity.CreatedOn = auditDate;
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.CreatedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        entry.Entity.ModifiedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        break;
                    case EntityState.Deleted:
                        break;
                    case EntityState.Modified:
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.ModifiedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }
            }
}

It works, But it's tightly coupling the DbContext with HttpContext which is not a good idea in case we'll expose the DbContext to a non-web environment. So I use this way:

public class ApplicationDbContext :
        IdentityDbContext<ApplicationUser, CustomRole, int, CustomUserLogin, CustomUserRole, CustomUserClaim>,
        IUnitOfWork
{
    public ApplicationDbContext()
            : base("ConnectionString")
        {
        }
        public ApplicationDbContext(string userName)
            : base("ConnectionString")
        {
            UserName = userName;
        }
    //Other codes
    public string UserName
        {
            get;
            private set;
        }
    public void auditFields()
    {
            var auditDate = DateTime.Now;
            foreach (var entry in this.ChangeTracker.Entries<BaseEntity>())
            {
                switch (entry.State)
                {
                    case EntityState.Detached:
                        break;
                    case EntityState.Unchanged:
                        break;
                    case EntityState.Added:
                        entry.Entity.CreatedOn = auditDate;
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.CreatedBy = UserName ?? "anonymouse";
                        entry.Entity.ModifiedBy = UserName ?? "anonymouse";
                        break;
                    case EntityState.Deleted:
                        break;
                    case EntityState.Modified:
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.ModifiedBy = UserName ?? "anonymouse";
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }
            }
    }
}

And in the Ioc config project (I'm using structureMap in another class library):

ioc.For<IUnitOfWork>()
                   .HybridHttpOrThreadLocalScoped()
                   .Use<ApplicationDbContext>()
                   .Ctor<string>().Is(HttpContext.Current.User.Identity.Name);

But when I run the application I'll get this error in above line:

Object reference not set to an instance of an object

It seems that it can't inject HttpContext.

Any idea?

Answer 1

Take a look at this link http://techbrij.com/service-layer-entity-framework-asp-net-mvc-unit-testing

The Author's solution looks like yours (but he used AutoFac instead of StructureMap). His "trick" to get the "Name" was Thread.CurrentPrincipal.Identity.Name;

Another thing, IMHO, I think you should use DateTimeOffSet instead of DateTime for the audit date. Using DateTimeOffSet you won't have problems with differents time zone. Like this:

DateTimeOffSet auditDate = DateTime.UtcNow;