在 LabelFor() 控件中设置文本格式

我正在尝试格式化价格标签，以便价格始终采用 0.00 格式，我在下面看到了一个类似的问题，它使用了与我类似的代码。我收到一个object reference not set to an instance of an object错误，我知道这是因为我正在打电话Model.Price但我对 MVC 很陌生，我不明白在加载页面之前如何设置Model.Price。

@Html.LabelFor(model => model.Price, "0.00", new { id = "priceLabel", Value = String.Format("{0:C}", Model.Price) })

下面是控制器代码：

[HttpGet]
    public ActionResult Contact()
    {
        ViewBag.Message = "Your contact page.";
        // set the paper style list
        List<SelectListItem> styles = new List<SelectListItem>();
        ViewBag.paperStyle = new SelectList(styles, "Value", "Text");
        // set the subject list
        List<SelectListItem> subjects = new List<SelectListItem>();
        ViewBag.subject = new SelectList(subjects, "Value", "Text");
        // set the number of pages list
        List<SelectListItem> numberOfPages = new List<SelectListItem>();
        ViewBag.Urgency = new SelectList(urgency, "Value", "Text");
        // set the document type list
        List<SelectListItem> documentTypes = new List<SelectListItem>();
        ViewBag.documentType = new SelectList(documentTypes, "Value", "Text");
        // set the academic level list
        List<SelectListItem> academicLevel = new List<SelectListItem>();
        ViewBag.academicLevel = new SelectList(academicLevel, "Value", "Text");
        // set the number of sources list
        List<SelectListItem> numberOfSources = new List<SelectListItem>();
        ViewBag.numberOfSources = new SelectList(numberOfSources, "Value", "Text");
        // set the currency list
        List<SelectListItem> currencies = new List<SelectListItem>();
        currencies.Add(new SelectListItem() { Text = "$", Value = "USD", Selected = true });
        currencies.Add(new SelectListItem() { Text = "£", Value = "GBP", Selected = false });
        currencies.Add(new SelectListItem() { Text = "€", Value = "EUR", Selected = false });
        ViewBag.currency = new SelectList(currencies, "Value", "Text");
        return View();
    }
    [HttpPost]
    public ActionResult Contact(WritingAppModel c)
    {
        if (ModelState.IsValid)
        {
            // send the email and process the payment
            // if payment is ready then send email
            if (isPaymentReady())
            {
                // send email
            }
        }
        return View();
    }
public class modelData
    {
        public string documentType { get; set; }
        public string numberOfPages { get; set; }
        public string urgency { get; set; }
    }
    public JsonResult getNewPrice(modelData dropdownValues)
    {
        // check for urgency first since that is the base price
        if (dropdownValues.urgency != null)
        {
            currentPrice = Convert.ToDecimal(dropdownValues.urgency);
            if (dropdownValues.documentType != null)
            {
                currentPrice = currentPrice + Convert.ToDecimal(dropdownValues.documentType);
                if (dropdownValues.numberOfPages != null)
                {
                    currentPrice = currentPrice * Convert.ToInt16(dropdownValues.numberOfPages);
                }
            }
        }
        // do something with value and return a decimal
        return Json(new { currentPrice = currentPrice }, JsonRequestBehavior.AllowGet);
    }

下面是视图代码：

@using (Html.BeginForm())
{
    @Html.ValidationSummary(true)
<div class="row">
    @Html.LabelFor(model => model.Name, "Name:")
    @Html.EditorFor(model => model.Name)
    @Html.ValidationMessageFor(model => model.Name)
</div>
<div class="row">
    @Html.LabelFor(model => model.Email, "Email:")
    @Html.TextAreaFor(model => model.Email, new { id = "email" })
    @Html.ValidationMessageFor(model => model.Email)
</div>
<div class="row">
    @Html.LabelFor(model => model.Topic, "Topic:")
    @Html.EditorFor(model => model.Topic)
    @Html.ValidationMessageFor(model => model.Topic)
</div>
<div class="row">
    @Html.LabelFor(model => model.Subject, "Subject:")
    @Html.DropDownListFor(model => model.Subject, (SelectList)ViewBag.subject, "--Select--", new { id = "subjectList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.Style, "Style:")
    @Html.DropDownListFor(model => model.Style, (SelectList)ViewBag.paperStyle, "--Select--", new { id = "paperStyleList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.DocumentType, "Document Type:")
    @Html.DropDownListFor(model => model.DocumentType, (SelectList)ViewBag.documentType, "--Select--", new { id = "documentTypeList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.AcademicLevel, "Academic Level:")
    @Html.DropDownListFor(model => model.AcademicLevel, (SelectList)ViewBag.academicLevel, "--Select--", new { id = "academicLevelList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.NumberOfPages, "Number of Pages/Words:")
    @Html.DropDownListFor(model => model.NumberOfPages, (SelectList)ViewBag.numberOfPages, "--Select--", new { id = "numberOfPagesList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.NumberOfSources, "Number of Sources:")
    @Html.DropDownListFor(model => model.NumberOfSources, (SelectList)ViewBag.numberOfSources, "--Select--", new { id = "numberOfSourcesList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.Urgency, "Urgency:")
    @Html.DropDownListFor(model => model.Urgency, (SelectList)ViewBag.urgency, "--Select--", new { id = "urgencyList" })
</div>
<div class="row">
    @Html.LabelFor(model => model.Spacing, "Spacing:")
    @Html.RadioButtonFor(model => model.Spacing, "Single") Single
    @Html.RadioButtonFor(model => model.Spacing, "Double") Double
</div>
<div class="row">
    @Html.LabelFor(model => model.Requirements, "Requirements:")
    @Html.TextAreaFor(model => model.Requirements)
</div>
<div class="row">
        @Html.DropDownListFor(model => model.Currency, (SelectList)ViewBag.currency, null, new { id = "currencyList" })
    <h2>
        @Html.LabelFor(model => model.Price, "{0:C}", new { id = "priceLabel" })
    </h2>
    <input type="submit" value="Submit" />
    <input type="reset" value="Reset" />
</div>
}