Question

我正在尝试在我的应用程序中的下拉列表中实现编辑和更新。下拉列表的值列表将从模型中显示。但所选值不会显示在下拉列表中。所选值也将作为下拉列表中的值列表填充。

我的模特：

public string State
public SelectList RegionList { get; set; }
public class Region
{
 public string ID { get; set; }
 public string Name { get; set; }            
}

查看

@foreach (var item in Model.AddressList)
{
    @Html.DropDownListFor(model => item.State, new SelectList(Model.Address.RegionList, "Value", "Text", Model.Address.RegionList.SelectedValue))                                                     
}

注意：
item.State已填充，但未显示该值填充并显示model.address.regionlist

控制器

public ActionResult EditAddress(AddressTuple tmodel,int AddressID)
{
    int country;
    string customerID = 1;
    List<AddressModel> amodel = new List<AddressModel>();
    amodel = GetAddressInfo(customerID, AddressID); // returns the selected value for dropdown
    foreach (var item in amodel)
    {
        country = item.CountryId;
    }            
    List<Region> objRegion = new List<Region>();
    objRegion = GetRegionList(id); // returns the list of values for dropdown
    SelectList objlistofregiontobind = new SelectList(objRegion, "ID", "Name", 0);
    atmodel.RegionList = objlistofregiontobind;

    tmodel.Address      = atmodel;
    tmodel.AddressList  = amodel;
    return View(tmodel);
}

要在下拉列表中进行编辑，将显示值列表。但不显示所选值。我的代码中有什么错误。任何建议。

编辑：

@Html.DropDownListFor(model => model.State, new SelectList(Model.RegionList, "ID", "Name",Model.State))

Answer 1

此

model => item.State

不会起作用，因为它从html帮助器中隐藏了从模型中获取下拉值的事实。实现此目的的正确方法是将foreach替换为for：

@for (int i=0; i<Model.AddressList.Count; i++)
{
    @Html.DropDownListFor(model => model.AddressList[i].State, new SelectList(Model.Address.RegionList, "Value", "Text", Model.Address.RegionList.SelectedValue))                                     
}

Answer 2

假设AddressList属性为IList<Something>，请尝试这样：

@for (var i = 0; i < Model.AddressList.Count; i++)
{
    @Html.DropDownListFor(
        model => model.AddressList[i].State, 
        new SelectList(Model.Address.RegionList, "Value", "Text")
    )
}

在Dropdownlist mvc4中编辑和更新

2 个答案: