为"Html.DropDownListFor"设置多个选定值

Question

我手上有两个字符串数组

`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显示此场景?我试过这样做

@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 = "" })

但是给出错误

操作符'=='不能应用于'string'和'string[]类型的操作数

有谁能指出解决这个问题的正确方法吗?

Answer 1

由于Model.Country是一个列表/数组，因此不应使用==，而应使用.Contains()来检查列表/数组中的值。

对于多重选择，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 = "" })

示例。net Fiddle