C# 从列表框中获取所选项目（使用Ajax填充）

我正在尝试从我的多选列表中获取所选项目。我真正想检索的只是一个选定的项目或选定的组，但组中的所有项目都足够了。我的列表一开始是空的，然后在使用Ajax选择不同的列表后填充

我的JQuery更改事件是这样的：

$("#institutions").change(function() {
                $.ajax({
                    type: 'POST',
                    url: '@Url.Action("FillGroupsAndFam")',
                    dataType: 'json',
                    data: { institutionId: Number($("#institutions").val()) },
                    success: function(model) {
                        $("#family-select").empty();
                        var $prevGroup, prevGroupName;
                        $.each(model.FamilyGroups, function() {                              
                            if (prevGroupName != this.Group.Name) {
                                $prevGroup = $(document.createElement("optgroup"))
                                .prop("label", this.Group.Name)
                                .appendTo("#family-select");
                            }
                                $(document.createElement("option"))
                                    .val(this.Value)
                                    .text(this.Text)
                                    .appendTo("#family-select");
                            prevGroupName = this.Group.Name;
                        });
                        $("#family-select").multiselect('rebuild');

     var famList = (from f in fam
        let famGroup = new SelectListGroup {Name = f.FamilyGroupName}
        from id in f.UserIds
        select new SelectListItem
        {
            Text = UserManager.FindById(id).UserName, Value = id, Disabled = true, Group = famGroup
        }).ToList();

    @Html.LabelFor(m => m.CreateModel.FamilyGroups)
    @Html.ListBoxFor(m => m.CreateModel.SelectedFamilyGroupId, Model.CreateModel.FamilyGroups, new {@class="form-control", @id="family-select"})

这将调用

FillGroupsAndFam

，它像这样填充我的列表：

$("#institutions").change(function() {
                $.ajax({
                    type: 'POST',
                    url: '@Url.Action("FillGroupsAndFam")',
                    dataType: 'json',
                    data: { institutionId: Number($("#institutions").val()) },
                    success: function(model) {
                        $("#family-select").empty();
                        var $prevGroup, prevGroupName;
                        $.each(model.FamilyGroups, function() {                              
                            if (prevGroupName != this.Group.Name) {
                                $prevGroup = $(document.createElement("optgroup"))
                                .prop("label", this.Group.Name)
                                .appendTo("#family-select");
                            }
                                $(document.createElement("option"))
                                    .val(this.Value)
                                    .text(this.Text)
                                    .appendTo("#family-select");
                            prevGroupName = this.Group.Name;
                        });
                        $("#family-select").multiselect('rebuild');

     var famList = (from f in fam
        let famGroup = new SelectListGroup {Name = f.FamilyGroupName}
        from id in f.UserIds
        select new SelectListItem
        {
            Text = UserManager.FindById(id).UserName, Value = id, Disabled = true, Group = famGroup
        }).ToList();

    @Html.LabelFor(m => m.CreateModel.FamilyGroups)
    @Html.ListBoxFor(m => m.CreateModel.SelectedFamilyGroupId, Model.CreateModel.FamilyGroups, new {@class="form-control", @id="family-select"})

在我看来，我是这样显示这个列表的：

$("#institutions").change(function() {
                $.ajax({
                    type: 'POST',
                    url: '@Url.Action("FillGroupsAndFam")',
                    dataType: 'json',
                    data: { institutionId: Number($("#institutions").val()) },
                    success: function(model) {
                        $("#family-select").empty();
                        var $prevGroup, prevGroupName;
                        $.each(model.FamilyGroups, function() {                              
                            if (prevGroupName != this.Group.Name) {
                                $prevGroup = $(document.createElement("optgroup"))
                                .prop("label", this.Group.Name)
                                .appendTo("#family-select");
                            }
                                $(document.createElement("option"))
                                    .val(this.Value)
                                    .text(this.Text)
                                    .appendTo("#family-select");
                            prevGroupName = this.Group.Name;
                        });
                        $("#family-select").multiselect('rebuild');

     var famList = (from f in fam
        let famGroup = new SelectListGroup {Name = f.FamilyGroupName}
        from id in f.UserIds
        select new SelectListItem
        {
            Text = UserManager.FindById(id).UserName, Value = id, Disabled = true, Group = famGroup
        }).ToList();

    @Html.LabelFor(m => m.CreateModel.FamilyGroups)
    @Html.ListBoxFor(m => m.CreateModel.SelectedFamilyGroupId, Model.CreateModel.FamilyGroups, new {@class="form-control", @id="family-select"})

我的

ViewModel

有以下功能：

[Display(Name="Family in Study")]
public IEnumerable<SelectListItem> FamilyGroups { get; set; }
public IEnumerable<SelectListItem> SelectedFamilyGroupId { get; set; }

[显示（Name=“研究中的家庭”）]
公共IEnumerable FamilyGroup{get；set；}
public IEnumerable SelectedFamilyGroupId{get；set；}

我通过将

SelectedFamilyGroupId

类型更改为

IEnumerable