'The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.'

Question

This question has been asked a lot of times. I think I solved my problem but since I am a beginner and still learning I need your reassurance.

I made a Extension method for the Logged In User But when I use it in my Controller it gives me the error in title.

System.ObjectDisposedException: 'The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.'

So I searched and experimented and adding this line of code in the controller solved my problem.

db.Users.Attach(LoggedUser);

However I am not sure if my answer is correct, since a lot of answers about this question were to disable the Lazy Loading but I didn't end up using it.

Something like this.

public class MyDbContext : DbContext
{
  public MyDbContext()
   {
    this.Configuration.LazyLoadingEnabled = false;
   }
}

Here is my Extension method:

 public static ApplicationUser GetLoggedInUserInDB(this System.Security.Principal.IPrincipal _User)
    {
        using (var db = new ApplicationDbContext())
        {
            string userId = _User.Identity.GetUserId();
            var LoggedUser = db.Users.Find(userId);
            return LoggedUser;
        }
    }

My Controller:

public class MainPageController : ApiController
{
    [Route("Personal_Project/Main_Page_Personal_Project/UserUnfo")]
    [ResponseType(typeof(string))]
    [Authorize]
    public IHttpActionResult GetUserInfo()
    {
        using (var db = new ApplicationDbContext())
        {
            var LoggedUser = User.GetLoggedInUserInDB();
            //db.Users.Attach(LoggedUser); // This is what I added to solve my problem.
            return Ok(new UserInfoModel
            {
                Name = LoggedUser.UserName,
                Reputation = LoggedUser.Reputation,
                UserLevel = LoggedUser.UserLevel
            });
        }
    }
}

So is 'My' solution here good? Just adding:

db.Users.Attach(LoggedUser);

Is it legit or this is not how we solve this problem. Any advice will be greatly appreciated

Added as requested:

StackTrace:

ex.StackTrace " at System.Data.Entity.Core.Objects.ObjectContext.get_Connection()\r\n
at System.Data.Entity.Core.Objects.ObjectQuery1.GetResults(Nullable1 forMergeOption)\r\n at System.Data.Entity.Core.Objects.ObjectQuery1.Execute(MergeOption mergeOption)\r\n at System.Data.Entity.Core.Objects.DataClasses.EntityReference1.Load(MergeOption mergeOption)\r\n at System.Data.Entity.Core.Objects.DataClasses.RelatedEnd.DeferredLoad()\r\n at System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.LoadProperty[TItem](TItem propertyValue, String relationshipName, String targetRoleName, Boolean mustBeNull, Object wrapperObject)\r\n at System.Data.Entity.Core.Objects.Internal.LazyLoadBehavior.<>c__DisplayClass7`2.b__2(TProxy proxy, TItem item)\r\n at System.Data.Entity.DynamicProxies.ApplicationUser_3D8410FBA1701532D53558B4E07B366CC45F4901DA609FCE10D652D704EEDD3C.get_CarGame()\r\n at PersonalProject.Controllers.MainPageController.GetUserInfo() in C:\Users\Jack\Desktop\PostPersonalProject\PersonalProject\PersonalProject\Controllers\MainPageController.cs:line 32" string

Answer 1

You're getting exception because of this: get_CarGame().

Code inside original post doesn't match your actual code.

Somewhere inside actual MainPageController.GetUserInfo you're trying to read ApplicationUser.CarGame. And yes, this is lazy loading issue.

GetLoggedInUserInDB returns instance of proxy class, derived from ApplicationUser, and disposes original context. When GetUserInfo tries to get CarGame property value, proxy attempts to read it from database, using disposed context. As a result, exception is being thrown.

If you really need CarGame inside UserInfoModel:

• either turn off lazy loading as shown above, and use eager loading;
• use projection (that is, Select) to retrieve user info as UserInfoModel in place. In this case there is no need in GetLoggedInUserInDB method at all.

Anyway, attaching LoggedUser to another context is not a way to go.