Question

我的控件中有以下Page_Load方法（System.Web.UI.UserControl）：

protected void Page_Load(object sender, EventArgs e)
{
    DropDownList ShowAssumptions = new DropDownList();
    List<string> list = new List<string>()
    {
        "test",
        "test2"
    };
    ShowAssumptions.DataSource = from i in list
                                 select new ListItem()
                                 {
                                     Text = i,
                                     Value = i
                                 };
    ShowAssumptions.DataBind();
}

然后，在我的.aspx中我有这个：

<asp:DropDownList id="ShowAssumptions" runat="server">
</asp:DropDownList>

但是，DropDownList永远不会被填充。我做错了什么？

Answer 1

只需将列表指定为数据源即可。另外我假设你不想在每个PostBack上重新加载列表。

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
         List<string> list = new List<string>()
         {
            "test",
            "test2"
         };
        ShowAssumptions.DataSource = list;
        ShowAssumptions.DataBind();
    }
}

Answer 2

如果你使用 ASP.NET WebForms，EF和Bootstrap 试试这个

<强> HTML

<div class="form-group">    

<label class="control-label" for="inputType">Lines: </label>                            

<asp:DropDownList ID="DropDownListFabricLines" CssClass="dropdown form-control" runat="server"></asp:DropDownList>

</div>

<强> C＃

var entities = new DababaseEntities();

List<FabricLineView> fabricLines =  entities .Line.Select(x=> new FabricLineView { ID = x.LineaID, Name = x.LineaNombre }).ToList();

DropDownListFabricLines.DataValueField = "ID";
DropDownListFabricLines.DataTextField = "Name";
DropDownListFabricLines.DataSource = fabricLines;
DropDownListFabricLines.DataBind();


public sealed class FabricLineView
{
    public int ID { get; set; }
    public string Name { get; set; }
}

Answer 3

protected void Page_Load(object sender, EventArgs e)
    {
        //Don't do this here!
        //DropDownList ShowAssumptions = new DropDownList();

        List<string> list = new List<string>()
        {
            "test",
            "test2"
        };
        this.ShowAssumptions.DataSource = from i in list
                                     select new ListItem()
                                     {
                                         Text = i,
                                         Value = i
                                     };
        this.ShowAssumptions.DataBind();
    }

Answer 4

  protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            foreach (string item in list)
            {
                ShowAssumptions.Items.Add(item);
            }
        }
    }

如何在webforms中加载页面之前填充下拉列表？

4 个答案: