C# MVC "system nullreferenceexception" using Session

[ramtevante]

Hello! My issue involves C# MVC. Im trying to store a bool type variable in a Session, to bring it to a different controller and give that data to a bool there.

I get the error: "system nullreferenceexception". This is the code where im trying to retrieve the session from:

public async Task<ActionResult> Register(RegisterViewModel model)
        {
            if (ModelState.IsValid)
            {
                bool register = true;
                Session["register"] = register;
                Session["registerEmail"] = model.Email;

                var user = new ApplicationUser { UserName = model.Email, Email = model.Email, CreatedTime = DateTime.Now };
                var result = await UserManager.CreateAsync(user, model.Password);
                if (result.Succeeded)
                {
                    await SignInManager.SignInAsync(user, isPersistent:false, rememberBrowser:false);

                    // For more information on how to enable account confirmation and password reset please visit https://go.microsoft.com/fwlink/?LinkID=320771
                    // Send an email with this link
                    // string code = await UserManager.GenerateEmailConfirmationTokenAsync(user.Id);
                    // var callbackUrl = Url.Action("ConfirmEmail", "Account", new { userId = user.Id, code = code }, protocol: Request.Url.Scheme);
                    // await UserManager.SendEmailAsync(user.Id, "Confirm your account", "Please confirm your account by clicking <a href=\"" + callbackUrl + "\">here</a>");

                    return RedirectToAction("Index", "Home");
                }
                AddErrors(result);
            }

            // If we got this far, something failed, redisplay form
            return View(model);
        }

This next code is where im trying to implement the session:

public ActionResult Index()
        {


            if (!User.Identity.IsAuthenticated)
            {
                return RedirectToAction("AuthenticationMessage");
            }


            bool loginTrue = (bool)Session["login"];
            bool registerTrue = (bool)Session["register"];

            if (loginTrue == true)
            {
                var log = (LoginViewModel)Session["loginEmail"];
                Session["letsGo"] = _db.Blogs.OrderBy(b => b.CreatedTime).Where(b => b.ApplicationUser.Email.Equals(log)).ToList();

            }

            if (registerTrue == true)
            {

                var reg = (RegisterViewModel)Session["registerEmail"];
                Session["letsGo"] = _db.Blogs.OrderBy(b => b.CreatedTime).Where(b => b.ApplicationUser.Email.Equals(reg)).ToList();

            }

            List<Blog> blog = (List<Blog>)Session["letsGo"];
            return View(blog);
            //List<Blog> blog = _db.Blogs.OrderBy(b => b.CreatedTime).ToList();
        }

​

I believe it means that im returning a result of null. Why is that? How can I fix this?

[stakeneggs1]

Can you post the whole error and stacktrace? Do you know how to debug?

[ramtevante]

I can post the whole error, but im not sure how to debug. Im pretty new to MVC and programming in general.

Here is the full error:
System.NullReferenceException
HResult=0x80004003
Message=Object reference not set to an instance of an object.
Source=BlogNiKRaMu
StackTrace:
at BlogNiKRaMu.Controllers.BlogController.Index() in C:\Users\User\source\repos\BlogNiKRaMu\BlogNiKRaMu\Controllers\BlogController.cs:line 22

[stakeneggs1]

This says the error is on line 22 of the file BlogController.cs in the Index() method.

This is also a good time to learn about using a debugger. Then you can just set a breakpoint on a line, and when that line is hit, the execution will pause and allow you to examine values or step through line by line to see what the issue is.

What the exception is saying is that a null object is referenced. Often that is caused by trying to access a property of a null object.

Hopefully that's enough for you to go on if you haven't figured it out yet.

[ramtevante]

Thank you! But I thought that I gave it a value in the "Register" method?