Question

我使用了下拉列表中的模型，

> public class Items
>     {
>         public int itemcategoryid { get; set; }
>         public string itemcategory { get; set; }
>         public int Itemsubcategoryid { get; set; }
>         public string Itemsubcategoryname { get; set; }
>     }

并在控制器代码下方

>             ItemViewModel catVM = new ItemViewModel();
>             List<Items> catlist = catVM.GetCategoryInfo();
>             ViewBag.categorylist = catlist;

使用HTML代码下方的绑定下拉列表后，该下拉列表已填充并选择默认名称作为itemcategory，但未传递itemcategory的ID，仅传递了POST的itemcategory名称。

 @Html.DropDownListFor(model => model.itemcategory, new SelectList(ViewBag.categorylist, "itemcategory", "itemcategory",  Model.itemcategory))

如果我在HTML代码下方使用其通过值，但未选择默认名称

  @Html.DropDownListFor(model => model.itemcategory, new SelectList(ViewBag.categorylist, "itemcategoryid", "itemcategory", Model.itemcategory))

使用下面的代码检索数据

using (OracleCommand cmd = new OracleCommand("PS_Category", conn))
                {
                    cmd.CommandType = System.Data.CommandType.StoredProcedure;
                    conn.Open();
                    OracleDataReader reader = cmd.ExecuteReader();
                    while (reader.Read())
                    {
                        Items listitems = new Items(); ;
                        listitems.itemcategoryid = Convert.ToInt32(reader["CATID"]);
                        listitems.itemcategory = reader["CATNAME"].ToString();
                        items.Add(listitems);
                    }
                }

实际上我想选择默认名称并传递其ID怎么可能呢？

Answer 1

之前在这里回答过，但有些人报告说这对他们不起作用； @Html.DropDownListFor how to set default value

如果这不起作用，请在此处选择列表类文档

https://docs.microsoft.com/en-us/dotnet/api/system.web.mvc.selectlist.-ctor?view=aspnet-mvc-5.2#System_Web_Mvc_SelectList__ctor_System_Collections_IEnumerable_System_String_System_String_System_String_System_Object_

这里提到您使用的构造函数使用最后一个参数作为选定值，因此您应该这样做；（最后传递model.itemcategoryid）

@Html.DropDownListFor(model => model.itemcategory, new SelectList(ViewBag.categorylist, "itemcategoryid", "itemcategory", Model.itemcategoryid))

如果上述答案对您不起作用，这是使用jquery的另一种方法；

添加一个类htmlattribute selectLoop;

@Html.DropDownListFor(model => model.itemcategoryId, new SelectList(ViewBag.categorylist, "itemcategoryid", "itemcategory"), new { @class="selectLoop" })

将此脚本添加到您的视图中；

@section scripts{
 <script>
 // when the document is ready (server is done loading)
 $(document).ready(function(){

   // loop through all those with selectLoop class
   $(".selectLoop").each(function(){

      // get the selected value and store to variable
      var selected = "@Model.itemCategoryId";

      // loop through all the option inside the select
      $(this).find("option").each(function(){

         // check if the value attribute matches the selected variable
         if($(this).attr("value") == selected){

            // if match, assign the option's selected attribute to true
            $(this).attr("selected",true);
         }
      });
   });
 });
 </script>
}

然后在您的shared / layout.cshtml中，在jquery和bootstrap之后添加@RenderSection("scripts", required: false)。见下文；

  @Scripts.Render("~/bundles/jquery")
  @Scripts.Render("~/bundles/bootstrap")
  @RenderSection("scripts", required: false)

Answer 2

对于多个下拉值，请使用它。对于插入值，请使用

ViewBag.DocumentId = new SelectList(_documentCategoryService.GetAll().OrderBy(a => a.Name), "Id", "Name");

对于编辑，您可以使用它。

ViewBag.DocumentId = new MultiSelectList(_documentCategoryService.GetAll(), "Id", "Name", _documentCategoryService.GetAllByExportId((int)id).Select(a => a.DocumentCategoryId).ToArray());

查看零件：

 <div class="row-fluid">
                <div class="span12">
                    <div class="control-group">
                        <label class="control-label">Documents Require</label>
                        <div class="controls controls-row">
                            @Html.DropDownList("DocumentId", null, htmlAttributes: new { @placeholder = "Select Documents", @class = "span6 chzn-select documentCategories", @tabindex = "8", @multiple = "multiple", @name = "DocumentId" })
                        </div>
                    </div>
                </div>
            </div>

对于单个DropdownValue。

ViewBag.BranchId = new SelectList(_branchService.GetAllByOrganizationId((User as CustomPrincipal).DefaultOrganizationId), "Id", "Name");


ViewBag.BranchId = new SelectList(_branchService.GetAllByOrganizationId((User as CustomPrincipal).DefaultOrganizationId), "Id", "Name", exportLetter.LcTransctionDetails.Transactions.BranchId);

<div class="span4">
                    <div class="control-group">
                        <label class="control-label">Branch</label>
                        <div class="controls controls-row">
                            @Html.DropDownList("BranchId", null, htmlAttributes: new { @class = "form-control", @id = "Branches" })
                        </div>
                    </div>
                </div>

在下拉列表中选择默认值，并通过ID MVC下拉列表

2 个答案: