Question

我有一个控制器，它为视图提供SelectList，然后为DropDownLists呈现多个SelectList。我现在希望DropDownLists具有默认选择的不同值。有没有办法做到这一点？

编辑：哦，当然我希望默认的值可以从我的模型中获得，例如Model.Dj1_Id等。

控制器：

    [HttpGet]
    public ActionResult EditPartyInfo(int ID)
    {
        Party prty = db.Partys.Find(ID);
        ViewBag.People = new SelectList(db.People, "Id", "Name");
        return View(prty);
    }

查看：

@model Musa.Models.Party

@using (Html.BeginForm("EditPartyInfo", "Events", FormMethod.Post))
{
    @Html.AntiForgeryToken()
    <!-- Some text input fields -->
    <div class="form-group">
        <label for="Dj1_Id">Dj 1</label>
        <div class="form-inline">
            @Html.DropDownList("Dj1_Id", ViewBag.People as SelectList, String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })
        </div>
    </div>
    <div class="form-group">
        <label for="Dj2_Id">Dj 2</label>
        <div class="form-inline">
            @Html.DropDownList("Dj2_Id", ViewBag.People as SelectList, String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })
        </div>
    </div>
    <div class="form-group">
        <label for="Dj3_Id">Dj 3</label>
        <div class="form-inline">
            @Html.DropDownList("Dj3_Id", ViewBag.People as SelectList, String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })
        </div>
    </div>
    <input type="submit" class="btn btn-primary" value="Los geht's" />
}

我实际上最终做了：

控制器：

    [HttpGet]
    public ActionResult EditPartyInfo(int ID)
    {
        Party prty = db.Partys.Find(ID);
        ViewBag.People = db.People;
        return View(prty);
    }

查看：

/*...*/
@Html.DropDownList("Dj1_Id", new SelectList(ViewBag.People, "Id", "Name", Model.Dj1_Id), String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })
/*...*/
@Html.DropDownList("Dj2_Id", new SelectList(ViewBag.People, "Id", "Name", Model.Dj2_Id), String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })
/*...*/
@Html.DropDownList("Dj3_Id", new SelectList(ViewBag.People, "Id", "Name", Model.Dj3_Id), String.Empty, new { @class = "form-control person-select", style = "width: 50%;" })

Answer 1

请尝试;

而不是

ViewBag.People as SelectList

此;

new SelectList(ViewBag.People, "Id", "Name", "Id value to select")

作为Html.DropDownList s

的第二个参数

Answer 2

SelectList有一个构造函数，您可以在其中传入所选对象，所以：

new SelectList(db.People, "Id", "Name", db.People.FirstOrDefault(x => x.Id == party.Dj1_Id)

我个人更喜欢使用IEnumerable<SelectListItem>，如此：

ViewBag.People = db.People.Select(x => new SelectListItem { Text = x.Name, Value = x.Id, Selected = x.Id == party.Dj1_Id);

无论哪种方式都应该有效。

从SelectList为DropDownLists设置不同的默认值

2 个答案: