在 Html.DropDownlistFor 中获取多个选定值

问题描述

@Html.DropDownListFor(m => m.branch, CommonMethod.getBranch("",Model.branch), "--Select--", new { @multiple = "multiple" })

@Html.DropDownListFor(m => m.division, CommonMethod.getDivision(Model.branch,Model.division), "--Select--", new { @multiple = "multiple" })

我有两个 DropDownListFor 实例.我想将之前为 Model.branch 和 Model.division 存储值的那些设置为 true.这些是存储 id 的字符串数组

I have two instances of DropDownListFor. I want to set selected as true for those which have previously stored values for Model.branch and Model.division. These are string arrays of stored ids

class CommonMethod
{
    public static List<SelectListItem> getDivision(string [] branchid , string [] selected)
    {
        DBEntities db = new DBEntities();
        List<SelectListItem> division = new List<SelectListItem>();
        foreach (var b in branchid)
            {
                var bid = Convert.ToByte(b);
                var div = (from d in db.Divisions where d.BranchID == bid select d).ToList();
                foreach (var d in div)
                {
                    division.Add(new SelectListItem { Selected = selected.Contains(d.DivisionID.ToString()), Text = d.Description, Value = d.DivisionID.ToString() });
                }
            }
        }

        return division;
    }
}

对于模型中的选定项，除法的返回值选择为真，但在视图侧未选择.

The returned value of division is selected as true for the selected item in the model, but on view side it is not selected.

推荐答案

使用 ListBoxFor 而不是 DropDownListFor:

@Html.ListBoxFor(m => m.branch, CommonMethod.getBranch("", Model.branch), "--Select--")

@Html.ListBoxFor(m => m.division, CommonMethod.getDivision(Model.branch, Model.division), "--Select--")

branch 和 division 属性显然必须是包含所选值的集合.

The branch and division properties must obviously be collections that will contain the selected values.

以及使用视图模型构建多选下拉列表的正确方法的完整示例:

And a full example of the proper way to build a multiple select dropdown using a view model:

public class MyViewModel
{
    public int[] SelectedValues { get; set; }
    public IEnumerable<SelectListItem> Values { get; set; }
}

将填充到控制器中:

public ActionResult Index()
{
    var model = new MyViewModel();

    // preselect items with values 2 and 4
    model.SelectedValues = new[] { 2, 4 };

    // the list of available values
    model.Values = new[]
    {
        new SelectListItem { Value = "1", Text = "item 1" },
        new SelectListItem { Value = "2", Text = "item 2" },
        new SelectListItem { Value = "3", Text = "item 3" },
        new SelectListItem { Value = "4", Text = "item 4" },
    };

    return View(model);
}

并在视图中:

@model MyViewModel
...
@Html.ListBoxFor(x => x.SelectedValues, Model.Values)

HTML 帮助程序将自动预选其值与 SelectedValues 属性匹配的项目.

It is the HTML helper that will automatically preselect the items whose values match those of the SelectedValues property.

这篇关于在 Html.DropDownlistFor 中获取多个选定值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！