如何将 ViewModel 对象添加到 TempData

问题描述

我有以下带有视图模型的控制器，如下所示 -

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Initiate(IFormCollection formCollection)
{
    var studentId = formCollection["studentid"].ToString();

    if (string.IsNullOrEmpty(studentId))
    {
        return NotFound(new { msg = "UnkNown student" });
    }

    Student student = await _context.Students.Include(s=>s.Parents).FirstOrDefaultAsync(s=>s.Id==studentId).ConfigureAwait(false);

    var dashboard = User.FindFirstValue(ClaimTypes.Role).ToLower();

    if (formCollection["bill"].Count > 0)
    {
        //Calculate the total bills and present a payment confirmation page
        List<int> billIds = new List<int>();
        foreach (var id in formCollection["bill"])
        {
            billIds.Add(Convert.ToInt32(id));
        }

        if (billIds.Count > 0)
        {
            List<Fee> fees = await _context.Fees.Where(f => billIds.Contains(f.Id)).ToListAsync().ConfigureAwait(false);

            string CustomerEmail = null;
            string CustomerPhone = null;
            string CustomerFirstName = null;
            string CustomerLastName = null;

            if (student.Parents.Any())
            {
                var parent = student.Parents.FirstOrDefault();

                CustomerEmail = parent?.Email;
                CustomerPhone = parent?.PhoneNumber;
                CustomerFirstName = parent?.OtherNames;
                CustomerLastName = parent?.Surname;
            }
            string TrxnRef = RandomStringGenerator.UpperAlphaNumeric(5) + student.Id.Substring(0,8);

            BillsPayviewmodel model = new BillsPayviewmodel
            {
                StudentId=student.Id,StudentName=student.FullName,PaymentItems=fees,TransactionRef= TrxnRef,CustomerPhone = CustomerPhone ?? student.PhoneNumber,CustomerEmail = CustomerEmail ?? student.Email,CustomerFirstname = CustomerFirstName ?? student.OtherNames,CustomerLastname = CustomerLastName ?? student.Surname,CustomerFullname=$"{CustomerFirstName} {CustomerLastName}",Currency = "NGN",AmountToPay=fees.Sum(a=>a.Amount),Callbackurl=$"/Payments/Status/{TrxnRef}"
            };

            TempData["PaymentDetails"] = model;
            return View("BillsPayConfirmation",model);
        }
    }
    else
    {
        TempData["msg"] = "<div class='alert alert-success'><i class='fa fa-check'></i> No outstanding bills found for student</div>";

        return RedirectToAction(dashboard,"dashboard");
    }
    return RedirectToAction();
}

当我添加将模型添加到临时数据的部分时，我意识到

TempData["PaymentDetails"] = model;

我得到以下内容

有没有办法将整个模型添加到 TempData 中，这样我就不需要在下一页重复生成 viewmodel 的过程？

解决方法

你必须修复你的代码：

 Student student = await _context.Students.Include(s=>s.Parents).FirstOrDefaultAsync(s=>s.Id==studentId).ConfigureAwait(false);
if (student==null) ....return error
....
.....

if (student.Parents!=null &&  student.Parents.Count() > 0)
{
.....
}

 BillsPayViewModel model = new BillsPayViewModel
            {
                StudentId=student.Id,StudentName=student.FullName,PaymentItems=fees,TransactionRef= TrxnRef,CustomerPhone = CustomerPhone ?? student.PhoneNumber,CustomerEmail = CustomerEmail ?? student.Email,CustomerFirstname = CustomerFirstName ?? student.OtherNames,CustomerLastname = CustomerLastName ?? student.Surname,Currency = "NGN",AmountToPay=fees.Sum(a=>a.Amount),Callbackurl=$"/Payments/Status/{TrxnRef}"
            };

          model.CustomerFullname=  model.CustomerFirstName==null || model.CustomerLastName==null?
     string.Empty: $"{model.CustomerFirstName} {model.CustomerLastName}";

}
 

,

经过一番挣扎，我遇到了 this SO question，它给了我问题所在的线索，结果证明问题在于 ASP.NET Core 中的 TempData（可能来自版本 5，因为我没有在其他版本中尝试过）没有包含对象的能力。

我试图向 TempData 添加一个对象，这就是问题的根源。解决方法是先序列化模型，然后再将其添加到 TempData 中，然后将其反序列化回我需要使用它的对象，如下所示

  TempData["PaymentDetails"] = JsonConvert.SerializeObject(model);

在我需要它的时候，按如下方式反序列化它

BillsPayViewModel paymentDetails = JsonConvert.DeserializeObject<BillsPayViewModel>((string)TempData["PaymentDetails"]);

我想这会为某人节省很多时间。