越来越多选择的价值观Html.DropDownlistFor [英] Getting Multiple Selected Values in Html.DropDownlistFor

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DropDownListFor的两个实例。我想设置选作如此那些有pviously存储值Model.branch和Model.division $ P $。这些存储的ID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;
    }
}

师的返回值被选作如此在模型中选择的项目，但在视图方面，它没有被选中。

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--")

的分支和分工属性必须显然是集合将包含选定的值。

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

和的正确的方式来建立一个多重选择下拉使用视图模型完整的例子：

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; }
}

这将在控制器填充

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);
}

和视图：

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

这是HTML帮手会自动preSELECT其值的项目匹配的 SelectedValues​​ 属性。

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