DropDownList内容不更新

我有一个下拉列表，获取基于3个其他控件（如下）的值的数据填充。DropDownList内容不更新

有2个问题，我有：

1）在初始页面加载底部的下拉列表是空的，只有与其他控件的一个触发回发后的数据填充。有没有简单的方法让它在初始页面加载时填充正确的数据？

2）如果我从代码隐藏中删除UpdatePanel.Update()，那么只要有一个由其他控件触发的回发，底部下拉列表中的数据就无法更新。下拉列表中的数据是否应该在这种情况下自动更新，而不需要UpdatePanel.Update()？

我希望这解释清楚，足以让某人明白我在这里所得到的。

<asp:SqlDataSource ID="srcTheatreList" runat="server" ConnectionString="<%$ ConnectionStrings:database %>" SelectCommand="SELECT theatreID, name FROM Theatre"></asp:SqlDataSource> 
<asp:SqlDataSource ID="srcMovieList" runat="server" ConnectionString="<%$ ConnectionStrings:database %>" SelectCommand="SELECT movieID, title FROM Movie"></asp:SqlDataSource> 
<asp:SqlDataSource ID="srcSessionTimes" runat="server" ConnectionString="<%$ ConnectionStrings:database %>" 
    SelectCommand="SELECT s.time FROM Session s INNER JOIN Movie m ON (s.movieID = m.movieID) INNER JOIN Theatre t ON (s.theatreID = t.theatreID) WHERE [email protected] AND [email protected] AND [email protected]"> 
    <SelectParameters> 
     <asp:ControlParameter Name="theatreID" ControlID="ddlTheatreList" PropertyName="SelectedValue" /> 
     <asp:ControlParameter Name="movieID" ControlID="ddlMovieList" PropertyName="SelectedValue" /> 
     <asp:ControlParameter Name="date" ControlID="txtDate" PropertyName="Text" DefaultValue="23/09/2012" /> 
    </SelectParameters> 
</asp:SqlDataSource> 

<asp:UpdatePanel ID="UpdatePanel" runat="server"> 
<ContentTemplate> 
    <table> 
    <tr><td>Select theatre:</td><td><asp:DropDownList ID="ddlTheatreList" runat="server" DataSourceID="srcTheatreList" DataTextField="name" DataValueField="theatreID" AutoPostBack="True"></asp:DropDownList></td></tr> 
    <tr><td>Select movie:</td><td><asp:DropDownList ID="ddlMovieList" runat="server" DataSourceID="srcMovieList" DataTextField="title" DataValueField="movieID" AutoPostBack="True"></asp:DropDownList></td></tr> 
    <tr><td>Select date:</td><td><asp:TextBox ID="txtDate" runat="server" AutoPostBack="True" Text="23/09/2012"></asp:TextBox><img id="calendarButton2" src="~/images/calendar.png" alt="" runat="server" /> 
    <asp:CalendarExtender ID="CalendarExtender" runat="server" TargetControlID="txtDate" TodaysDateFormat="d MMMM yyyy" DaysModeTitleFormat="MMMM yyyy"></asp:CalendarExtender></td></tr> 
    <tr><td>Select time:</td><td><asp:DropDownList ID="ddlSessionTimes" runat="server" AutoPostBack="True"></asp:DropDownList></td></tr> 
    </table><br /> 
</ContentTemplate> 
</asp:UpdatePanel>

代码隐藏：

Protected Sub UpdateSessionTimes(sender As Object, e As EventArgs) Handles ddlMovieList.SelectedIndexChanged, ddlTheatreList.SelectedIndexChanged, txtDate.TextChanged 
    Dim dv As DataView = srcSessionTimes.Select(DataSourceSelectArguments.Empty) 
    ddlSessionTimes.DataSource = dv 
    ddlSessionTimes.DataTextField = "time" 
    ddlSessionTimes.DataValueField = "time" 
    ddlSessionTimes.DataBind() 
    UpdatePanel.Update() 
End Sub

来源

2012-10-27 tneb

自己的方式与选择参数来访问SqlDataSource的是错的.. 这里是一个示例代码..

<asp:SqlDataSource ID="SqlDataSourceGridView" runat="server" 
    ProviderName="System.Data.SqlClient" 
    SelectCommand="SELECT [Name],[Address] FROM [Table_Emp] where Id = @Id" 
    OnSelecting="SqlDataSourceGridView_Selecting"> 

    <SelectParameters> 
     <asp:Parameter Name="Id" Type="Int32" /> 
    </SelectParameters> 

</asp:SqlDataSource> 

3) in Selecting event method put parameter value to the command 

protected void SqlDataSourceGridView_Selecting(object sender, SqlDataSourceSelectingEventArgs e) 
{ 
    e.Command.Parameters["@Id"].Value = (int)(Id ?? 0); // nullable ind is not applicable here 
}

和不写任何问题的意见:)

来源

2012-10-27 14:26:58

DropDownList内容不更新

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