Share User data between different action in the same controller in MVC - entity-framework

Question

I want to store globally the object User (that is the table USER in my db) in my HomeController, in that way i don't have to instantiate it in every single action.
I found the following solution that works pretty fine
public class HomeController : Controller
{
private DatabaseContext db = new DatabaseContext();
private User currentUser;
private User CurrentUser
{
get
{
if (User.Identity.IsAuthenticated)
//This function returns the object "User" (table USER in db) based on the PK of the table
currentUser = CustomDbFunctions.GetUserEntityFromUsername(User.Identity.Name, db);
return currentUser;
}
}
public ActionResult Index()
{
if (User.Identity.IsAuthenticated)
return View(CurrentUser);
else
return Redirect("login");
}
}
I'd like to know if there's a better (or more elegant) way to achieve the same goal.
Please note that i'm not using the MembershipProvider.

Answer 1

In your example the user object is instantiated in every single action (in contrast to what you said). This is because actions are usually invoked per http request and controller instances are disposed after each use.
Your code shares the instance structurally (you don't have to repeat the code) which is ok but what about sharing the code between different controllers? I'd suggest to refactor your GetUserEntityFromUsername a little bit so that you retrieve the object only once per request, using the Items container to get the request scope:
public class CustomDbFunctions
{
const string itemsUserKey = "_itemsUserKey";
public static User GetUserEntityFromUsername( IPrincipal principal, DatabaseContext db )
{
if ( principal == null || principal.Identity == null ||
!principal.Identity.IsAuthenticated
)
return null;
if ( HttpContext.Current.Items[itemsUserKey] == null )
{
// retrieve the data from the Db
var user = db.Users.FirstOrDefault( u => u.Name == User.Identity.Name );
HttpContext.Current.Items[itemsUserKey] = user;
}
return (User)HttpContext.Current.Items[itemsUserKey];
}
This way your wrapper takes care of retrieving the instance from the database once per request.
Note that this requires sharing your database context as entities should not be reused on different contexts. Fortunately, this can be done in a similar way:
public class CustomDbFunctions
{
const string dbUserKey = "dbUserKey";
public static DatabaseContext CurrentDatabaseContext
{
get
{
if ( HttpContext.Current.Items[dbUserKey] == null )
{
DatabaseContext ctx = new DatabaseContext(); // or any other way to create instance
HttpContext.Current.Items[dbUserKey] = ctx;
}
return (DatabaseContext)HttpContext.Current.Items[dbUserKey];
}
}
This way, the context instance, shared per request, is always available as
CustomDbFunctions.CurrentDatabaseContext