Asp.net 通过ViewModel从多个DropDownList向控制器传递值时出错

我正在尝试创建一个表单DropDownList，该表单由SelectList创建，根据学生用户关联的不同[银行]帐户生成。到目前为止，我已经能够成功地为所有帐户创建两个下拉列表，但是当我提交表单时，我得到一个错误：没有为此对象定义无参数构造函数。

我不确定这个错误的原因是什么，我想我正确地设置了控制器和视图来处理不同的值，但是我不确定传入的ViewModel是否正确

账户模型（转账操作结果中使用的银行账户）

TransferFundsViewModel（这是构建了我的强类型视图的类，我正在尝试将其传递给我的控制器。）

在我的控制器内转移资金方法

[HttpGet]
    public ActionResult TransferFunds()
    {
        //Get logged in user
        var studentProfile = db.UserProfiles.Local.SingleOrDefault(u => u.UserName == User.Identity.Name)
            ?? db.UserProfiles.SingleOrDefault(u => u.UserName == User.Identity.Name);
        //Get student account associated with logged in user
        var student = db.Students.Find(studentProfile.UserId);
        //Get accounts associated with student account
        var accounts = db.Accounts.Where(x => x.StudentID == student.UserId);

        var selectionList = new SelectList(accounts, "AccountID", "AccountName");

        var vm = new TransferFundsViewModel { ListOfSourceAccounts = selectionList, ListOfDestinationAccounts = selectionList };

        return View(vm);
    }

    [HttpPost]
    public ActionResult TransferFunds(TransferFundsViewModel viewModel)
    {
        if (ModelState.IsValid)
        {
            try
            {
                AccountManager manager = new AccountManager();
                Account srcAccount = db.Accounts.Find(viewModel.SelectedSourceAccountId);
                Account destAccount = db.Accounts.Find(viewModel.SelectedDestinationAccountId);

                manager.TransferMoney(srcAccount, destAccount, viewModel.TransferAmount); //From Account Manager
                db.SaveChanges();
            }
            catch (DataException)
            {
                ModelState.AddModelError("", "Something went wrong, transfer could not be completed.");
            }
        }
        return RedirectToAction("AccountSummary");
    }

AccountManager（该类包含实际转移资金的逻辑。）

最后，转移资金视图

@model eBank.ViewModels.TransferFundsViewModel
@using (Html.BeginForm()) {
    <fieldset>
        <legend>Transfer Funds</legend>

        <div class="editor-label">
            Source Account
        </div>
        <div class="editor-field">
            @Html.DropDownListFor(viewModel => viewModel.ListOfSourceAccounts, Model.ListOfSourceAccounts, "Choose an Account")
        </div>

        <div class="editor-label">
            Destination Account
        </div>
        <div class="editor-field">
            @Html.DropDownListFor(viewModel => viewModel.ListOfDestinationAccounts, Model.ListOfDestinationAccounts, "Choose an Account")
        </div>

        <div class="editor-label">
            Transfer Amount
        </div>
        <div class="editor-field">
            @Html.EditorFor(viewModel => viewModel.TransferAmount)
        </div>

        <p>
            <input type="submit" value="Transfer" />
        </p>
    </fieldset>
}

@model eBank.ViewModels.TransferFundsViewModel
@使用（Html.BeginForm（））{
转移资金
来源帐户
@Html.DropDownListFor（viewModel=>viewModel.ListOfSourceAccounts，Model.ListOfSourceAccounts，“选择帐户”）
目的地帐户
@Html.DropDownListFor（viewModel=>viewModel.ListOfDestinationAccounts，Model.ListOfDestinationAccounts，“选择帐户”）
转账金额
@EditorFor（viewModel=>viewModel.TransferAmount）


}

创建dropdownlist时，需要更改第一个参数以使用SelectedSourceAccountId

改变

@Html.DropDownListFor(viewModel => viewModel.ListOfSourceAccounts, Model.ListOfSourceAccounts, "Choose an Account")

为了

与其他下拉列表相同

---

现在，您的模型应该有了值，srccount和destcount对象将不会为空。

Wow，这真是太快了！非常感谢。我不敢相信修复这么简单。。。我花了至少一个半小时来试验不同的解决方案。

    public class AccountManager
{
    public void TransferMoney(Account srcAccount, Account destAccount, decimal transferAmount)
    {
        if (srcAccount.AccountTotal >= transferAmount)
        {
            srcAccount.AccountTotal -= transferAmount;
            destAccount.AccountTotal += transferAmount;
        }
    }
}

@model eBank.ViewModels.TransferFundsViewModel
@using (Html.BeginForm()) {
    <fieldset>
        <legend>Transfer Funds</legend>

        <div class="editor-label">
            Source Account
        </div>
        <div class="editor-field">
            @Html.DropDownListFor(viewModel => viewModel.ListOfSourceAccounts, Model.ListOfSourceAccounts, "Choose an Account")
        </div>

        <div class="editor-label">
            Destination Account
        </div>
        <div class="editor-field">
            @Html.DropDownListFor(viewModel => viewModel.ListOfDestinationAccounts, Model.ListOfDestinationAccounts, "Choose an Account")
        </div>

        <div class="editor-label">
            Transfer Amount
        </div>
        <div class="editor-field">
            @Html.EditorFor(viewModel => viewModel.TransferAmount)
        </div>

        <p>
            <input type="submit" value="Transfer" />
        </p>
    </fieldset>
}

@Html.DropDownListFor(viewModel => viewModel.ListOfSourceAccounts, Model.ListOfSourceAccounts, "Choose an Account")

@Html.DropDownListFor(viewModel => viewModel.SelectedSourceAccountId, Model.ListOfSourceAccounts, "Choose an Account")