从下拉列表中检索所有选定的Id's值

我有一个名为InvestigatorGroupData的实体，其如下:

[DataContract]
public class InvestigatorGroupData
{
        [DataMember]
        public int InvestigatorGroupId { get; set; }
        [DataMember]
        public string InvestigatorGroupName { get; set; }
        [DataMember]
        public bool HasGameAssignment { get; set; }
}

我已经创建了以下视图模型:

public class InvestigatorGroupModel
{
    public IEnumerable<InvestigatorGroupData> groupList {get;set;}
    public int SelectedInvestigatorGroupId { get; set; }
}

并将其传递给视图，如下所示:

InvestigatorGroupModel groupModel = new InvestigatorGroupModel();
GameClient proxy = new GameClient();
groupModel.groupList = proxy.GetInvestigatorGroups(User.Identity.GetUserId());
proxy.Close();
return View("SelectGroup", groupModel);

我的视图的下拉列表看起来像这样:
@Html.DropDownListFor(m => m.SelectedInvestigatorGroupId,new SelectList(Model.groupList, "InvestigatorGroupId", "InvestigatorGroupName"))

我希望用户能够选择InvestigatorGroupName，并返回相关的InvestigatorGroupData(而不仅仅是Selected Id)。到目前为止，只有SelectedInvestigatorGroupId被返回/发布，groupList为null

非常感谢你的帮助!

InvestigatorGroupModel groupModel = new InvestigatorGroupModel();
GameClient proxy = new GameClient();
groupModel.groupList = proxy.GetInvestigatorGroups(User.Identity.GetUserId());
proxy.Close();
//Save the list of InvestigatorGroupData objects to be retrieved later
HttpContext.Current.Session["GroupList"] = groupModel.groupList;
return View("SelectGroup", groupModel);

//Grab the list of InvestigatorGroupData objects that was saved before
IEnumerable<InvestigatorGroupData> groupList = (IEnumerable<InvestigatorGroupData>)HttpContext.Current.Session["GroupList"];
int investigatorGroupId = groupModel.SelectedInvestigatorGroupId;
InvestigatorGroupData selectedGroup = groupList.Single(l => l.investigatorGroupId == investigatorGroupId);