回发后如何维护下拉列表选择的值？

Question

我正在使用 Asp.Net MVC4。我在视图页面中有一个 html select。我想在回发后保持 selected 值。

查看：

@using (Html.BeginForm("TaxMaster", "Masters", FormMethod.Get))
{
     <div>
     <select id="ddlSearchBy" name="ddlSearchBy" style="width: 150px">
     <option value="TaxCode">Tax Code</option>
     <option value="TaxDescription">Tax Description</option>
     <option value="ClassDescription">Class Description</option>
     <option value="ZoneName">Zone Name</option>
     </select>
     <input type="text" class="input-small" name="txtSearchValue" id="txtSearchValue" placeholder="Enter Search Value" style="width: 225px" />&ensp;
     <button type="button" id="btnSearch" class="btn btn-small btn-primary">Search</button>
      </div>
 }

MastersController.cs:

  [HttpGet]
  public ActionResult TaxMaster(string txtSearchValue, string ddlSearchBy)
  {
        TaxMaster objTaxTable = new TaxMaster();
        objTaxTable.TaxTable = new List<moreInsights_offinvoice_taxmaster>();
        objTaxTable.TaxTable = GetTaxMasterTable(ddlSearchBy, txtSearchValue);
        return View(objTaxTable);
  }

在这里，在过滤器中，我有一个下拉列表、文本框和按钮。当我 select 下拉菜单并单击搜索按钮时，selected 值被传递给控制器 class 并且它 returns 过滤后的数据被传递给视图。但是下拉列表不会保持 selected 值。它再次重置。如何在 MVC 中维护下拉 selected 值？

Answer 1

public ActionResult TaxMaster(string txtSearchValue, string ddlSearchBy)
{
    TaxMaster objTaxTable = new TaxMaster();
    objTaxTable.TaxTable = new List<moreInsights_offinvoice_taxmaster>();
    objTaxTable.TaxTable = GetTaxMasterTable(ddlSearchBy, txtSearchValue);
    ViewBag.SelectedOption=ddlSearchBy;
    return View(objTaxTable);
}

string selectedOption = ViewBag.SelectedOption;

<select id="ddlSearchBy" name="ddlSearchBy" style="width: 150px">
 <option value="TaxCode" selected="@(selectedOption == "TaxCode" ? "selected" : "")">Tax Code</option>
 <option value="TaxDescription" selected="@(selectedOption == "TaxDescription" ? "selected" : "")">Tax Description</option>
 <option value="ClassDescription" selected="@(selectedOption == "ClassDescription" ? "selected" : "")">Class Description</option>
 <option value="ZoneName" selected="@(selectedOption == "ZoneName" ? "selected" : "")">Zone Name</option>
</select>

Answer 2

<select class="form-control" id="TipoTarjeta" name="TipoTarjeta">
<option <%= Convert.ToString(Request.Form["TipoTarjeta"] != null ? Request.Form["TipoTarjeta"] : "" ) == "" ? "selected" : "" %>>Seleccione
</option>
<option <%= (Convert.ToString(Request.Form["TipoTarjeta"] != null ? Request.Form["TipoTarjeta"] : "").ToLower() == "visa" ? "selected" : "") %>>Visa</option>
<option <%= (Convert.ToString(Request.Form["TipoTarjeta"] != null ? Request.Form["TipoTarjeta"] : "").ToLower()  == "mastercard" ? "selected" : "") %>>Mastercard</option>
<option <%= (Convert.ToString(Request.Form["TipoTarjeta"] != null ? Request.Form["TipoTarjeta"] : "").ToLower()  == "american express" ? "selected" : "") %>>American Express</option>
<option <%= (Convert.ToString(Request.Form["TipoTarjeta"] != null ? Request.Form["TipoTarjeta"] : "").ToLower()  == "otra" ? "selected" : "") %>>Otra</option>
</select>

回发后如何维护下拉列表选择的值？

How to maintain dropdownlist selected value after postback?

c#

asp.net-mvc

asp.net-mvc-4

html-select

dropdown