具有數據表的數據綁定下拉列表並添加自定義值

Question

我正在將我的下拉列表與數據表進行數據綁定。我需要在下拉列表中添加一個項目，該項目必須是選擇的第一個項目..我嘗試了許多方法，但沒有任何效果。

ddlCountry.Items.Add("--Select--");
ddlCountry.DataTextField = "Country";
ddlCountry.DataValueField = "Country";
ddlCountry.DataSource = dt;
ddlCountry.DataBind();

Answer 1

您的頁面聲明：

<asp:dropdownlist id="ddlCountry" AppendDataBoundItems="true" runat="server" >
    <asp:ListItem Value="0" Text="[ Select ]" Selected="True"></asp:ListItem>
</asp:dropdownlist>

AppendDataBoundItems="true" is the key.

您的代碼背后：

ddlCountry.DataTextField = "Country";
ddlCountry.DataValueField = "Country";
ddlCountry.DataSource = dt;
ddlCountry.DataBind();

Answer 2

嘗試這個

 ddlCountry.DataTextField = "Country";
 ddlCountry.DataValueField = "Country";
 ddlCountry.DataSource = dt;
 ddlCountry.DataBind();
 ddlCountry.Items.Insert(0, new ListItem("Select Country", "0"));

Answer 3

添加數據之前先綁定數據

ddlCountry.DataTextField = "Country";
ddlCountry.DataValueField = "Country";
ddlCountry.DataSource = dt;
ddlCountry.DataBind();
ddlCountry.Items.Add("--Select--");