使用linq查詢填充ListBox-未設置值

Question

誰能告訴我為什么這不能將ListItems的值設置為ID？ 值和文本都以DISPLAY_NAME的形式出現

  lstSelected.DataSource = entities.User
     .Where(x => SelectedItems.Contains(x.ID))
     .Select(x => new ListItem { Text = x.DISPLAY_NAME, Value = x.ID })
     .ToList<ListItem>();

  lstSelected.DataBind();

Answer 1

嘗試設置DisplayMember和ValueMember屬性（如果使用asp.net，則設置DataTextField和DataValueField ）

lstSelected.DisplayMember = "DISPLAY_NAME";
lstSelected.ValueMember = "ID";
lstSelected.DataSource = entities.User
     .Where(x => SelectedItems.Contains(x.ID))
     .ToList();
lstSelected.DataBind();

Answer 2

您有2個選項（兩種方式都使用錯誤）：

設置DataSource ， DataTextField和DataValueField ：

lstSelected.DataSource = entities.User
       .Where(x => SelectedItems.Contains(x.ID))
       .ToList<ListItem>();

lstSelected.DataTextField = "DISPLAY_NAME";
lstSelected.DataValueField = "ID";

lstSelected.DataBind();

或實例化ListItem並將其添加到您的ListBox ：

List<ListItem> mySelectedItems  = entities.User
       .Where(x => SelectedItems.Contains(x.ID))
       .Select(x => new ListItem { Text = x.DISPLAY_NAME, Value = x.ID })
       .ToList<ListItem>();

foreach(ListItem item in mySelectedItems)
{
    lstSelected.Items.Add(item);
}
lstSelected.DataBind();