asp.net MVC5 DropDownListFor中bool?類型賦值為null的解決辦法

使用ToString() 將null轉換為string即可

@Html.DropDownListFor(model => model.AllowedPublished,　　new List<SelectListItem> {　　new SelectListItem() { Text = "未審核", Value = (null as bool?).ToString() },　　new SelectListItem() { Text = "已通過", Value = "true" },　　new SelectListItem() { Text = "未通過", Value = "false" }})