如何将选定值设置为ListBox

我用调试器检查了 MultiSelectList 值已更改。所以我看到,在选择其值之后 Value = true; .

但我没有看到。运行时,所选值不可见。最后我试了 ViewBag , ViewData , ListBox() 还有几件事。我不明白什么?

这是我的控制员:

public ActionResult Edit(int id)
        {
            UserDto user = _userService.GetUserById(id);

            var companiesSelectList = new MultiSelectList(_companyService.GetCompanies(), "Id", "Name", user.Companies.Select(x => x.Id.ToString()).ToArray());


            TempData["CompaniesList"] = companiesSelectList;
            return View(user);
        }

我的观点:

 <div class="col-md-10">
    @Html.ListBoxFor(model => model.Companies, (MultiSelectList)TempData["CompaniesList"], new { @class = "form-control", @required = "required", @multiple = "multiple" })
            </div>

我用这个做视觉化

   $(document).ready(function () {

        $('#Companies').select2({

            placeholder: 'Please Select Company',
            maximumSelectionSize: 15,
            width: 400,
        });
    });