Question

我在我的控制器中使用此方法向ViewBag添加一些列表，该列表由两个操作使用：Create和Edit。列表已正确设置，某些项目已将Selected属性设置为true。

    private void AddUsersAndTrucksListsToViewBag(string[] selectedUsers, int[] selectedTrucks)
    {
        ViewBag.UsersList = uow.UsersRepository
            .GetAll(_siteId)
            .Where(u => u.IsActive)
            .Select(u => new SelectListItem()
            {
                Value = u.Id,
                Text = $"{u.Name} {u.Surname}",
                Selected = selectedUsers != null && selectedUsers.Contains(u.Id)
            })
            .ToArray();

        ViewBag.TrucksList = uow.OspRepository
            .GetAllTrucks(_siteId)
            .Select(t => new SelectListItem()
            {
                Value = t.Id.ToString(),
                Text = $"{t.Codename} {t.Manufacturer} {t.Model}",
                Selected = selectedTrucks != null && selectedTrucks.Contains(t.Id)
            })
            .ToArray();
    }

在Edit视图中：

    <div class="form-group">
        @Html.Label("Osoby", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.SelectedUserIds, (SelectListItem[])ViewBag.UsersList, new { @class = "form-control", multiple = "multiple" })
        </div>
    </div>

    <div class="form-group">
        @Html.Label("Samochody", htmlAttributes: new {@class = "control-label col-md-2"})
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.SelectedTruckIds, (SelectListItem[]) ViewBag.TrucksList, new {@class = "form-control", multiple = "multiple"})
        </div>
    </div>

在Create视图中完全相同：

    <div class="form-group">
        @Html.Label("Osoby", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.SelectedUserIds, (SelectListItem[])ViewBag.UsersList, new { @class = "form-control ", multiple = "multiple" })
        </div>
    </div>

    <div class="form-group">
        @Html.Label("Samochody", htmlAttributes: new {@class = "control-label col-md-2"})
        <div class="col-md-10">
            @Html.DropDownListFor(model => model.SelectedTruckIds, (SelectListItem[]) ViewBag.TrucksList, new {@class = "form-control ", multiple = "multiple"})
        </div>
    </div>

问题是在Edit视图中一切正常。但在Create视图中，只有第二个列表正确呈现了selected HTML属性。这可以在截图

上看到

这有什么问题？我发现它可能是由于ViewBag属性名称与某些Model属性名称相同，但它不是。两个列表都有multiple属性。

这是由ListBoxFor()

生成的HTML

<select class="form-control " id="SelectedUserIds" multiple="multiple" name="SelectedUserIds">
<option value="525b1890-942f-4fb4-96de-56e04b6ca196">Jan Kowalski</option>
<option value="5b0e1c01-0e46-436c-aa9b-ac63e66d691f">Adam Pawlak</option>
</select>

<select class="form-control " id="SelectedTruckIds" multiple="multiple" name="SelectedTruckIds">
<option selected="selected" value="3">425[O]21 MAN 12.232</option>
</select>

新截图：

Html.DropDownList对于特定视图中的特定列表不起作用

0 个答案: