c# – 当值在数组中时选择的MVC5 Razor html.dropdownlist for s

我有这个观点：

@model MyProject.Web.API.Models.AggregationLevelConfViewModel

[...]

@Html.DropDownListFor(m => m.Configurations[0].HelperCodeType,(SelectList)Model.HelperCodeTypeItems,new { id = "Configurations[0].HelperCodeType" })

ViewModel是：

public class AggregationLevelConfViewModel
{
    private readonly List<GenericIdNameType> codeTypes;
    private readonly List<GenericIdNameType> helperCodeTypes;

    public IEnumerable<SelectListItem> CodeTypeItems
    {
        get { return new SelectList(codeTypes,"Id","Name"); }
    }

    public IEnumerable<SelectListItem> HelperCodeTypeItems
    {
        get { return new SelectList(helperCodeTypes,"Name"); }
    }

    public int ProductionOrderId { get; set; }

    public string ProductionOrderName { get; set; }

    public IList<Models.AggregationLevelConfiguration> Configurations { get; set; }

    public AggregationLevelConfViewModel()
    {
        // Load CodeTypes to show it as a DropDownList
        byte[] values = (byte[])Enum.GetValues(typeof(CodeTypes));

        codeTypes = new List<GenericIdNameType>();
        helperCodeTypes = new List<GenericIdNameType>();

        for (int i = 0; i < values.Length; i++)
        {
            GenericIdNameType cType = new GenericIdNameType()
            {
                Id = values[i].ToString(),Name = EnumHelper.GetDescription((CodeTypes)values[i])
            };

            if (((CodeTypes)values[i]) != CodeTypes.NotUsed)
                codeTypes.Add(cType);

            helperCodeTypes.Add(cType);
        }
    }
}

而Models.AggregationLevelConfiguration是：

public class AggregationLevelConfiguration
{
    public byte AggregationLevelConfigurationId { get; set; }
    public int ProductionOrderId { get; set; }
    public string Name { get; set; }
    public byte CodeType { get; set; }
    public byte HelperCodeType { get; set; }
    public int PkgRatio { get; set; }
    public int RemainingCodes { get; set; }
}

我需要在这些属性中设置选定的值：

public IEnumerable<SelectListItem> CodeTypeItems
{
    get { return new SelectList(codeTypes,"Name"); }
}

public IEnumerable<SelectListItem> HelperCodeTypeItems
{
    get { return new SelectList(helperCodeTypes,"Name"); }
}

但我无法在新的SelectList中设置它(codeTypes,“Id”,“Name”);或新的SelectList(helperCodeTypes,“Name”);因为所选值位于Configurations数组中：fields AggregationLevelConfiguration.CodeType和AggregationLevelConfiguration.HelperCodeType.

我想我必须在View中设置选定的值,但我不知道该怎么做.

如何设置所选值？