<Bind(Exclude:="CurrentPrice")>在MVC4中不起作用

Question

我正在用ASP.NET MVC4写这篇文章，并且一直在尝试在表单中有一个字段，其中一个字段被排除在写入之外。我在AuctionsController.vb文件中有以下模型，它控制表单：

Function Create(<Bind(Exclude:="CurrentPrice")> test_auction As Models.Auction) As ActionResult
            Dim categoryList = New SelectList(New Object() {"Automotive", "Electronics", "Games", "Home"})
            ViewBag.CategoryList = categoryList
            Return View()
        End Function

视图Create.vbhtml如下所示：

lType MVCAuction.Models.Auction

@Code
    ViewData("Title") = "Create"
End Code

<h2>Create</h2>

@Using Html.BeginForm()
    @*@Html.AntiForgeryToken()*@
    @Html.ValidationSummary(True)

    @<fieldset>
        <legend>Auction</legend>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.Category)
        </div>
        <div class="editor-field">
            @*@Html.EditorFor(Function(model) model.Category)*@
            @Html.DropDownListFor(Function(model) model.Category, DirectCast(ViewBag.CategoryList, SelectList))
            @Html.ValidationMessageFor(Function(model) model.Category)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.Title)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.Title)
            @Html.ValidationMessageFor(Function(model) model.Title)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.Description)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.Description)
            @Html.ValidationMessageFor(Function(model) model.Description)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.ImageURL)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.ImageURL)
            @Html.ValidationMessageFor(Function(model) model.ImageURL)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.StartTime)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.StartTime)
            @Html.ValidationMessageFor(Function(model) model.StartTime)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.EndTime)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.EndTime)
            @Html.ValidationMessageFor(Function(model) model.EndTime)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.StartPrice)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.StartPrice)
            @Html.ValidationMessageFor(Function(model) model.StartPrice)
        </div>

        <div class="editor-label">
            @Html.LabelFor(Function(model) model.CurrentPrice)
        </div>
        <div class="editor-field">
            @Html.EditorFor(Function(model) model.CurrentPrice)
            @Html.ValidationMessageFor(Function(model) model.CurrentPrice)
        </div>

        <p>
            <input type="submit" value="Create" />
        </p>
    </fieldset>
End Using

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@Section Scripts
    @Scripts.Render("~/bundles/jqueryval")
End Section

当我在浏览器中进入表单并输入数据时，它仍然显示“(变量名称)是必需的”；如下所示：

​

为什么绑定排除功能不起作用？

Answer 1

在我学习本教程时，我意识到AuctionsController中Create函数的<Bind(Exclude:="CurrentPrice")>部分并不是导致CurrentPrice字段仍然是必需字段的问题。

虽然我使用的是MVC4而不是C#，但这里的帖子回答了我的问题：What does a questionmark (?) mean in a function declaration in C#

这是在变量类型周围使用问号，比如：Decimal?，这样当用户在网页上填写表单时，变量就不是必需的了。

希望这对和我有同样问题的人有所帮助！