Entity Framework Saving User when record is Modified - asp.net

Question

When a Record gets updated in my Database, I need to be able to save who edited it.
Currently in my Repository I do this
pt.ModifiedBy = HttpContext.Current.User.Identity.Name;
There has to be a better way of doing this or is this only method?

Answer 1

By using HttpContext.Current.User you're tightly coupling your DbContext with HttpContext which is not a good idea in case you'll expose your DbContext to a non-web environment (UnitTesting, WCF, WPF etc).
You can use System.Security.Principal.IIdentity instead, just like exposed in ASP.NET (System.Web.HttpContext.Current.User.Identity), WCF (System.ServiceModel.OperationContext.Current.ServiceSecurityContext.PrimaryIdentity) and Thread (Thread.CurrentPrincipal.Identity).
Then, have your DbContext accept IIdentity in its constructor, and whenever the context initialized pass the appropriate IIdentity (from your current context).
For example (based on #qujck answer):
public class MyContext : DbContext
{
private readonly IIdentity _identity;
public DbContext(IIdentity identity)
{
this._identity = identity;
}
public override int SaveChanges()
{
//you may need this line depending on your exact configuration
//ChangeTracker.DetectChanges();
foreach (DbEntityEntry o in GetChangedEntries())
{
IEntity entity = o.Entity as IEntity;
entity.ModifiedBy = this._identity.Name;
}
return base.SaveChanges();
}
}
// Usage (ASP.NET):
var context = new DbContext(System.Web.HttpContext.Current.User.Identity);

Answer 2

IMO the best option is to handle all the auditing in one place - your unit of work (DbContext). This is easily achieved by having all of your Poco objects implement a common interface, such as IEntity.
Here's an example:
public class MyContext : DbContext
{
public override int SaveChanges()
{
//you may need this line depending on your exact configuration
//ChangeTracker.DetectChanges();
foreach (DbEntityEntry o in GetChangedEntries())
{
IEntity entity = o.Entity as IEntity;
entity.ModifiedBy = HttpContext.Current.User.Identity.Name;
}
return base.SaveChanges();
}
private IEnumerable<DbEntityEntry> GetChangedEntries()
{
return new List<DbEntityEntry>(
from e in ChangeTracker.Entries()
where e.State != System.Data.EntityState.Unchanged
select e);
}
}