ASP.NET MVC 让@Html.DropDownList显示默认值

在使用@Html.DropDownList的过程中，发现它的用法很局限，比如在加载的时候显示设定的默认项或者调整它的显示样式，在网上查了一些资料，终于把这个问题解决了。

    一、View代码

        

@using (Ajax.BeginForm("Edit", new AjaxOptions() { OnSuccess = "afterEdit" }))
{
    @Html.HiddenFor(model => model.ID)
    @Html.HiddenFor(model => model.isUsed)

<div style="padding: 40px 40px 30px 50px;">
    <table style="font-size:12px" align="center">
        <tr>
            <td>@Html.Label("评论人职务：")</td>
            <td>@Html.DropDownList("YzPositionCriticsID", ViewData["CriticsPositionType"] as SelectList)</td>
        </tr>
        <tr>
            <td>@Html.Label("被评论人职务：")</td>
            <td>@Html.DropDownList("YzPositionEvaluationID", ViewData["EvaluationPosition"] as SelectList)</td>
        </tr>
        <tr>
            <td>@Html.Label("权重：")</td>
            <td>@Html.TextBoxFor(model => model.Weight)</td>
        </tr>
    </table>
</div>

}

    二、Controller代码    

        

public ActionResult Edit(string id)
{
    //6.1根据ID从数据库中查出要修改的相关数据
    Guid Gid = new Guid(id);
    Model.DTO.YzWeightEntityDTO weight = weightBLL.LoadEnities(u => u.ID == Gid).FirstOrDefault().ToDto();

    //6.2查询YzPositionEntity实体的数据
    List<Model.DTO.YzPositionEntityDTO> positionList = positionBLL.LoadEnities().ToList().Select(s => s.ToDto()).ToList();

    //6.3将YzPositionEntity的数据封装到 SelectList中，制定要生成下拉框选项的value和text属性
    SelectList selList1 = new SelectList(positionList, "ID", "PositionType", weight.YzPositionCriticsID);
    SelectList selList2 = new SelectList(positionList, "ID", "PositionType",weight.YzPositionEvaluationID);

    //6.4把生成的集合放到ViewData中
    ViewData["CriticsPositionType"] = selList1;
    ViewData["EvaluationPosition"] = selList2;
    return View(weight);
}

     在这里需要注意的是：SelectList selList1 = new SelectList(list,"","",***),这里的***就是下拉框加载时候要显示的默认值。

     

     最后的显示效果如下：