ViewBag不工作

Question

我正在尝试创建一个MVC站点，并且我对ViewBag有了一些了解。

就像它不能包含元素一样。

我正在使用MVC 4。

这是我在控制器中的功能：

public ActionResult Create()
{
    ViewBag.DiscID = new SelectList(entities.Disc, "ID", "ID");
    ViewBag.StarID = new SelectList(entities.Star, "ID", "Name");

    ViewBag.Num = 7;

    return View();
}

这是我的创作视图：

@model Movies.Models.StarAndRole

@{
    ViewBag.Title = "Create";

    int num;

    int.TryParse(ViewBag.Num, out num);
}

<h2>Create</h2>


@using (Html.BeginForm())
{
    @Html.AntiForgeryToken()

    <div class="form-horizontal">
        <h4>StarAndRole</h4>
        <h3>num is = @num</h3>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        <div class="form-group">
            @Html.LabelFor(model => model.StarID, "Star", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("StarID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.StarID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.Description, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Description, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Description, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            @Html.LabelFor(model => model.DiscID, "Disc Num", htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.DropDownList("DiscID", null, htmlAttributes: new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.DiscID, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </div>
    </div>
}

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

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

在我看来，我在ViewBag中放入的所有内容都是空的。

我做错什么了？

提前谢谢你！

Answer 1

Int.TryParse方法接受字符串( int值的表示)。但是，您将动态类型传递给该方法。这应该会给你一个错误。

如果您知道您正在从操作方法中设置Int值，则在您的视图中，您可以简单地读取它如下

int num = ViewBag.Num;

更好的解决方案是将要传递给视图的数据添加到视图模型中。

public class YourCreateVm
{
  public string Description { set;get;}
  public int Num { set;get;}
  public List<SelectListItem> Disks { set;get;}
  public int SelectedDiskId { set;get;}
}

在你的视野中

public ActionResult Create()
{
  var vm = new YourCreateVm { Num = 7 };
  vm.Disks = entities.Disc.Select(s=> new SelectListItem
                                    { Value=s.ID.ToString(), Text =s.Name}).ToList();
  return View(vm);
}

在你看来

@model YourCreateVm
@using(Html.BeginForm())
{
  <p>My num is : @Model.Num <p>
  @Html.TextBoxFor(s=>s.Description)
  @Html.DropDownListFor(s=>s.SelectedDiskId, Model.Disks)
  <input type="submit" />    
}