Question

我有一个可从下拉列表中选择的名称列表。名称是从数据源而不是从ListItem中提取的。我想在没有选择的情况下将框留空。我怎样才能做到这一点？

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
    DataSourceID="SqlDataSource2" DataTextField="director" 
    DataValueField="director">
    <!--<asp:ListItem Text="Please Select Director" Value="-1"/>-->
</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ 
    ConnectionStrings:dvdsConnectionString %>" ProviderName="<%$ 
    ConnectionStrings:dvdsConnectionString.ProviderName %>" 
    SelectCommand="SELECT [director] FROM [dvds]">
</asp:SqlDataSource>

Answer 1

尝试将AppendDataBoundItems="True"添加到代码中，并将<asp:ListItem Selected="True"></asp:ListItem>添加为项目

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" 
    DataSourceID="SqlDataSource2" DataTextField="director" 
    DataValueField="director" AppendDataBoundItems="True">

    <asp:ListItem Selected="True"></asp:ListItem>

</asp:DropDownList>
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ 
    ConnectionStrings:dvdsConnectionString %>" ProviderName="<%$ 
    ConnectionStrings:dvdsConnectionString.ProviderName %>" 
    SelectCommand="SELECT [director] FROM [dvds]">
</asp:SqlDataSource>

下拉列表中的默认选择

1 个答案: