c# - 验证 MVC 4 中的单个选择下拉列表

Question

我有一个具有如下属性的模型:

[Required]
public int SingleSelect { get; set; }

然后我在 Controller 中设置了一个 SelectList 并将其传递给 viewbag

public ActionResult Index()
    {
        ViewBag.SingleSelectList = new SelectList(new[]
                                      {
                                          new {ID="0",Name="-- Select --"},
                                          new {ID="1",Name="Select 1"},
                                          new{ID="2",Name="Select 2"},
                                          new{ID="3",Name="Select 3"},
                                      },
                        "ID", "Name", 0);


        return View();
    }

然后在 View() 上，我使用以下方法呈现一个漂亮的下拉框:

@Html.LabelFor(obj => obj.SingleSelect, new { @class = "control-label"})
@Html.DropDownListFor(obj => obj.SingleSelect, ViewBag.SingleSelectList as SelectList)
@Html.ValidationMessageFor(obj => obj.SingleSelect)

<button class="btn btn-primary" type="submit">Validate!</button>

如果用户没有在提交表单时做出选择(仍在选项“-- Select --”)，我如何让验证工作显示错误？

Answer 1

你可以尝试两种方法，首先

[Required, Range(1, Int32.MaxValue)]
public int SingleSelect { get; set; }

或更改您的 SelectList:

ViewBag.SingleSelectList = new SelectList(new[]
{
    new {ID="0",Name="-- Select --", Value=""},
    new {ID="1",Name="Select 1"},
    new{ID="2",Name="Select 2"},
    new{ID="3",Name="Select 3"},
},
"ID", "Name", 0);