get user from cookie and sign that user in mvc Identity - asp.net-mvc

Question

I have an Asp MVc web project. In order to sell product, the user should register or login to my website. After choosing its product, the user will redirect to bank gateway through PaymentAction method:
public String PaymentAction( TransAction Model )
{
try
{
Payment ob = new Payment();
Model.amount = 100000.ToString();
string result = ob.pay(Model.amount);
//, User.Identity.GetUserId()
/*
the result var is a string that contains the response from pay.ir/send
which contains: status, transId, errorCode, errorMessage and all things that
exist in JsonParameter
*/
JsonParameters Parmeters = JsonConvert.DeserializeObject<JsonParameters>(result);
// in this point the payment was successful and you can add info to your database
if ( Parmeters.status == 1 )
{
Response.Redirect("https://pay.ir/payment/gateway/" + Parmeters.transId);
}
else
{
return "error code : " + Parmeters.errorCode + "<br />" + "message " + Parmeters.errorMessage;
}
return "";
}
catch ( Exception exp )
{
return "error" + exp.Message;
}
}
after payment, the user redirect to my website through the following url:
http://www.mymvcapp.com/HelpMeToBuildMyExtraordinaryYear/VerifyPayment
and here is the VerifyPayment method:
[HttpPost]
[AllowAnonymous]
public ActionResult VerifyPayment( VerifyResult Vresult )
{
try
{
if ( !string.IsNullOrEmpty(Request.Form["transId"]) )
{
Payment ob = new Payment();
string result = ob.verify(Request.Form["transId"].ToString());
JsonParameters Parmeters = JsonConvert.DeserializeObject<JsonParameters>(result);
if ( Parmeters.status == 1 )
{
var userId = User.Identity.GetUserId();
var user = db.Users.Where(u => u.Id == userId).FirstOrDefault();
user.SuccessfullPayment = true;
user.FactorNo = User.Identity.GetUserId();
user.TraceNo = Request.Form["traceNumber"];
user.TransId = int.Parse(Request.Form["transId"]);
user.CardNo = Request.Form["cardNumber"];
user.PurchasedDate = DateTime.Now;
user.State = Parmeters.status;
user.Message = Request.Form["message"];
db.Entry(user).State = System.Data.Entity.EntityState.Modified;
db.SaveChanges();
Vresult.success = true;
Vresult.TransActionID += Request.Form["transId"].ToString();
Vresult.Amount += Parmeters.amount.ToString();
Vresult.SuccessMessage = "successful payment";
return RedirectToAction("Index", "DownloadEbook", new { traceNumber = user.TraceNo , factorNumber = user.FactorNo, purchaseDate =Utils.Funcs.ObtainPersianDate( (DateTime)user.PurchasedDate ) });
}
else
{
Vresult.error = true;
Vresult.ErrorMessage = "error code " + Parmeters.errorCode + "<br />" + "Errr meesafe " + Parmeters.errorMessage;
}
}
}
catch ( Exception ex )
{
Vresult.error = true;
Vresult.ErrorMessage = ex.Source+"\t"+ex.InnerException + "\t" + ex.Message+"ERRR";
}
return View(new AllNeededModels() { VerifyResult = Vresult });
as we can see the user must be logged in in order to complete the sale process. but after redirecting from bank to above url (VerifyPayment), the user is NOT logged in and the code will return a null exception.
the question is how should I keep user logged in after redirecting from bank to my website?
or how can get user from cookie and sign that user in?

Answer 1

the problem is araised in the process of getting user. we should use this code in order to get user:
var user = System.
Web.
HttpContext.
Current.
GetOwinContext().
GetUserManager<ApplicationUserManager>().
FindById(userId);
note that the correct approach is as above. the following code produces the problem. doNOT use it to obtain current user:
var user = db.Users.Where(u => u.Id == userId).FirstOrDefault();