Question

下面的代码使我＆＃34;对象引用未设置为对象的实例＆＃34;。我知道这是因为模型没有创建，但我不明白为什么？为什么AnnuityDetail.cshtml中的foreach循环不通过我创建并从Controller发送的cList循环？

控制器操作：

public ActionResult AnnuityDetail(FormCollection form)
    {
        List<Calculation> cList = new List<Calculation>();
        Calculation calc = new Calculation();
        calc.Date = Convert.ToDateTime(form["startdate"]);
        calc.InvoiceAmount = 2000;
        calc.InterestRate = Convert.ToDouble(form["InterestRate"]);
        calc.InterestAmount = (Convert.ToDouble(form["PresentValue"]) * Convert.ToDouble(form["InterestRate"]) / 360 * 30);
        calc.Amortization = (2000 - (Convert.ToDouble(form["PresentValue"]) * Convert.ToDouble(form["InterestRate"]) / 360 * 30));
        calc.PresentValue = Convert.ToDouble(form["PresentValue"]) - calc.Amortization;
        calc.StartValue = Convert.ToDouble(form["PresentValue"]);
        cList.Add(calc);
        for (int i = 0; i < Convert.ToInt32(form["PaymentPeriods"]); i++)
        {
            Calculation calcBefore = cList.Last();
            calc = new Calculation();
            calc.Date = calcBefore.Date.AddMonths(1);
            calc.InvoiceAmount = 2000;
            calc.InterestRate = Convert.ToDouble(form["InterestRate"]);
            calc.InterestAmount = (calcBefore.PresentValue * calc.InterestRate / 360 * 30);
            calc.Amortization = (calc.InvoiceAmount - (calcBefore.PresentValue * calc.InterestRate / 360 * 30));
            calc.PresentValue = calcBefore.PresentValue - calc.Amortization;
            cList.Add(calc);
        }
        return View(cList);
    }

View1（带表格）

@using (Html.BeginForm("AnnuityDetail", "Calculation")) //Runs AnnuityDetail
{
    <div class="calculateBox">
                            <label for="calcOption">Choose value to calculate:</label>
                            <select form="anFormCalcInput" id="calcOption" title="Choose what value you want to calculate">
                                <option value="anPMT">Payment (PMT)</option>
                                <option value="anI">Interest (I)</option>
                                <option value="anFV">Future value (FV)</option>
                                <option value="anPV">Present value (PV)</option>
                            </select>
                        </div>
                        <div class="calculateBox" background-color="#777777">
                            @Html.Label("Present value (PV)")
                            @Html.TextBox("PresentValue")
                            @Html.Label("Future value")
                            @Html.TextBox("FutureValue")
                            @Html.Label("Interest rate")
                            @Html.TextBox("InterestRate") <br />
                            <input type="radio" name="advanceOrArrears" id="inAdvance" value="inAdvance" /> In advance<br />
                            <input type="radio" name="advanceOrArrears" id="inArrears" value="inArrears" /> In arrears
                        </div>
                        <div class="calculateBox">
                            <label for="startDate">Start date:</label>
                            <input type="date" id="anStartDate" name="startdate" title="Choose start date for your calculation" /><br />
                            @Html.Label("Payment frequency")
                            <select form="anFormCalcInput" id="anPmtFreq" title="Choose the payment frequency, for example: Every month">
                                <option value="Monthly">Monthly</option>
                                <option value="Quarterly">Quarterly</option>
                                <option value="Yearly">Yearly</option>
                            </select><br /><br />
                            @Html.Label("No of payment periods")
                            @Html.TextBox("PaymentPeriods")
                            @Html.Label("Date time convention")
                            <select form="anFormCalcInput" id="anDTC" title="Choose your Date time convention">
                                <option value="360360">360/360</option>
                                <option value="365365">365/365</option>
                            </select><br /><br />
                            <input type="submit" id="anCalcBtn" class="calcBtn" name="anSubmitBtn" value="Calculate" title="Calculate your calculation" />
                        </div>
}

视图2（AnnuityDetail）：

@model IEnumerable<CalcFactory.Models.Calculation>
<table cellspacing="0" width="80%" id"detailTable">
<thead>
    <tr>
        <th>
            Row
        </th>
        <th>
            Date
        </th>
        <th>
            Invoice amount
        </th>
        <th>
            Interest rate
        </th>
        <th>
            Interest amount
        </th>
        <th>
            Amortization
        </th>
        <th>
            Capital balance
        </th>
        <th></th>
    </tr>
</thead>
@{var rowID = 1;}
@{var cellID = 1;}
@foreach (var item in Model) { //In this loop I get my error message, it can't find cList objects
    <tr id="@rowID">
        <td align="center">
            @rowID
        </td>
        <td align="center" id="A-@cellID">
            @Html.DisplayFor(modelItem => item.Date)
        </td>
        <td align="center" id="B-@cellID">
            @Html.DisplayFor(modelItem => item.InvoiceAmount)
        </td>
        <td align="center" id="C-@cellID">
            @Html.DisplayFor(modelItem => item.InterestRate)
        </td>
        <td align="center" id="D-@cellID">
            @Html.DisplayFor(modelItem => item.InterestAmount)
        </td>
        <td align="center" id="E-@cellID">
            @Html.DisplayFor(modelItem => item.Amortization)
        </td>
        <td align="center" id="F-@cellID">
            @Html.DisplayFor(modelItem => item.PresentValue)
        </td>
    </tr>
    rowID++;
    cellID++;
}

Answer 1

您的表单不包含“PaymentPeriods”的任何字段，因此该值未初始化。 for循环立即触及其结束条件。

如果PaymentPeriods应该来自表单但不能编辑，请尝试添加一个隐藏字段，其中包含您需要的值，但是它应该在客户端上吗？

您的@Html.DisplayFor(modelItem => item.Date)不应该是@Html.DisplayFor(item => item.Date)吗？ modelItem不是在任何地方使用的东西吗？

您能否尝试将var item更改为Calculation item并查看属性是否仍未解决？

@foreach (Calculation item in Model) { //In this loop I get my error message, it can't find cList objects
    <tr id="@rowID">
        <td align="center">
            @rowID
        </td>
        <td align="center" id="A-@cellID">
        @Html.DisplayFor(item => item.Date)
    </td>

返回从控制器到视图的对象列表

1 个答案: