为“Html.DropDownListFor”设置多个值

Question

我手头有两个字符串数组

`mdm.Country` - Contains all the countries that needs to be displayed on the drop down.
`Model.Country` - Contains multiple selected items that needs to be marked as selected on the 
drop down.

如何使用Html.DropDownListFor来显示这种情况？ 我尝试过这样的事情

                                @Html.DropDownListFor(n => n.Country, mdm.Country.Select
(d => { return new SelectListItem() { Selected = (d.ToString() == Model.Country), Text = d, Value = d }; }), null, new { @class = "custom", @multiple = "" })

但是给出了一个错误

运算符'=='不能应用于'string'和'string[]类型的操作数

谁能指出解决这个问题的正确方法。

Answer 1

由于Model.Country是一个列表/数组，所以不应该使用==而是使用.Contains()来检查列表/数组中的值是否。

对于多选，建议使用Html.ListBoxFor()

@Html.ListBoxFor(n => n.Country, 
                    mdm.Country
                    .Select(x => new SelectListItem
                    {
                        Selected = Model.Country.Contains(x),
                        Text = x,
                        Value = x
                    })
                    , 
                    new { @class = "custom", @multiple = "" })

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