我之前发过一个类似的问题，但没有一个答案有效，我一直在寻找解决方案。我的情况，我有一个带有下拉列表的编辑窗口webform（注意：为避免混淆，我只使用Telerik扩展来装饰webform）：
<%@ Page Language="VB" CodeFile="EditFormVB.aspx.vb" Inherits="EditFormVB" %>
<%@ Register Namespace="CustomBoundField" TagPrefix="custom" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Edit Pop-up</title>
</head>
<body class="">
<form id="form1" runat="server">
<div>
<script type="text/javascript">
function CloseAndRebind(args) {
GetRadWindow().BrowserWindow.refreshGrid(args);
GetRadWindow().close();
}
function GetRadWindow() {
var oWindow = null;
if (window.radWindow) oWindow = window.radWindow; //Will work in Moz in all cases, including clasic dialog
else if (window.frameElement.radWindow) oWindow = window.frameElement.radWindow; //IE (and Moz as well)
return oWindow;
}
function CancelEdit() {
GetRadWindow().close();
}
</script>
<asp:ScriptManager ID="ScriptManager2" runat="server" />
<telerik:RadFormDecorator ID="RadFormDecorator1" runat="server" Skin="Vista" DecoratedControls="All" />
<br />
<br />
<asp:DetailsView ID="DetailsView1" DataKeyNames="ID" runat="server" AutoGenerateRows="False"
GridLines="None" DataSourceID="detailsSqlDataSource" Height="50px" Width="125px"
BorderWidth="0" CellPadding="0" CellSpacing="7">
<Fields>
<asp:BoundField DataField="TS_DESCRIPTION" HeaderText="TS_DESCRIPTION" SortExpression="TS_DESCRIPTION" />
<asp:BoundField DataField="TS_TITLE" HeaderText="TS_TITLE" SortExpression="TS_TITLE" />
<asp:CommandField ShowEditButton="True" />
<asp:CommandField ShowInsertButton="True" />
</Fields>
</asp:DetailsView>--%>
<telerik:RadScriptManager ID="RadScriptManager1" runat="server" />
<telerik:RadFormDecorator ID="RadFormDecorator1" runat="server" Skin="Vista" />
<br />
<br />
<asp:DetailsView ID="DetailsView1" runat="server" Height="400px" Width="745px"
AutoGenerateRows="False" DataKeyNames="TS_ID" DataSourceID="SqlDataSource2"
EnableModelValidation="True">
<Fields>
<asp:TemplateField HeaderText="Category">
<EditItemTemplate>
<%--<asp:DropDownList ID="TTCategory" runat="server" DataSourceID="ReqCategoryData" SelectedValue='<%# Bind("TS_NAME") %>' />--%>
<asp:DropDownList DataSourceID="ReqCategoryData" DataTextField="ReqCategory" DataValueField="ReqCategory"
ID="reqCategoryDropDown" runat="server" AppendDataBoundItems="true" AutoPostBack="true" >
</asp:DropDownList>
</EditItemTemplate>
</asp:TemplateField>
<asp:CommandField ButtonType="Button" EditText="Update" ShowEditButton="True"
ShowCancelButton="True">
<ItemStyle HorizontalAlign="Center" />
</asp:CommandField>
</Fields>
</asp:DetailsView>
</div>
</form>
</body>
</html>
在后面的代码中，我正在为下拉列表设置数据源，并使用函数在DB初始加载页面时查询我想要设置为所选值的值的名称：
Partial Class EditFormVB
Inherits System.Web.UI.Page
Public Shared category_Name As String = ""
Dim ddlDataSource As New SqlDataSource
Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init
DetailsView1.DefaultMode = DetailsViewMode.Edit
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Me.Page.Title = "Editing record"
''Setup DropDownList SqlDataSource
ddlDataSource.ID = "ReqCategoryData"
Page.Controls.Add(ddlDataSource)
ddlDataSource.ConnectionString = ConfigurationManager.ConnectionStrings("TTPRODReportsQuery").ConnectionString
ddlDataSource.SelectCommand = "SELECT TS_NAME AS ReqCategory FROM dbo.TS_SELECTIONS WHERE (TS_FLDID = 5299 AND TS_STATUS = 0) ORDER BY TS_NAME"
Dim args As New DataSourceSelectArguments
ddlDataSource.Select(args)
''Set max length of Title field to 70 characters
Dim dvrTest As DetailsViewRowCollection = DetailsView1.Rows
Dim TitleTB As TextBox = dvrTest.Item(0).Cells(1).Controls(0)
TitleTB.Attributes.Add("onkeydown", "isMaxLen(this)")
TitleTB.Attributes.Add("maxlength", "70")
Dim myDDL As DropDownList = DetailsView1.FindControl("reqCategoryDropDown")
''Perform dropdown list population operations
If Page.IsPostBack = False Then
Dim ticket_ID As String = getDataKey(DetailsView1)
''Fetch Category ID
Dim sqlText As String = "SELECT TS_REQCATEGORY FROM USR_ITFAC WHERE (TS_ID = " + ticket_ID + ") "
Dim reqDataReader As SqlDataReader = GetDataReader(sqlText)
reqDataReader.Read()
Dim category_ID As String = reqDataReader(0)
''Fetch Category name using the categoryID and set as selected value in dropdown list
sqlText = "SELECT TS_NAME FROM TS_SELECTIONS WHERE (TS_ID = " + category_ID + ") "
reqDataReader = GetDataReader(sqlText)
reqDataReader.Read()
category_Name = reqDataReader(0)
myDDL.DataBind()
myDDL.Selectedvalue = category_Name //<--this value gets set only when debugging,
End If
End Sub
Private Function GetDataReader(ByVal sqlText As String) As SqlDataReader
Dim dr As SqlDataReader
Dim sqlConn As SqlConnection = New SqlConnection(ConfigurationManager.ConnectionStrings("TTPRODReportsQuery").ConnectionString)
sqlConn.Open()
Dim sqlCmd As SqlCommand = New SqlCommand(sqlText, sqlConn)
dr = sqlCmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection)
Return dr
End Function
End Class
下拉列表会正确填充，但是当我尝试设置该值时，它不反映页面加载的时间;只需填充下拉列表，并且在标记中没有设置任何值，因此默认情况下会显示第一个值。奇怪的是，当我调试时，当我单步执行该函数时，该值似乎已设置，就好像一旦函数退出并继续加载页面就会重置selectedvalue。感谢任何帮助或见解
解： 在完成执行后Page_Load后，必须添加一个单独的函数，该函数从DropDownList调用onLoad。仍未解决的问题是DropDownList在Page_Load之后重新绑定。
在HTML中：
<asp:DropDownList DataSourceID="ReqCategoryData" DataTextField="ReqCategory" DataValueField="ReqCategory"
ID="reqCategoryDropDown" runat="server" AutoPostBack="true" OnLoad="DDL_DataBound">
代码背后
Public Shared category_Name As String = ""
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Me.Page.Title = "Editing record"
''Setup DropDownList SqlDataSource
ddlDataSource.ID = "ReqCategoryData"
Page.Controls.Add(ddlDataSource)
ddlDataSource.ConnectionString = ConfigurationManager.ConnectionStrings("TTPRODReportsQuery").ConnectionString
ddlDataSource.SelectCommand = "SELECT TS_NAME AS ReqCategory FROM dbo.TS_SELECTIONS WHERE (TS_FLDID = 5299 AND TS_STATUS = 0) ORDER BY TS_NAME"
Dim args As New DataSourceSelectArguments
ddlDataSource.Select(args)
''Set max length of Title field to 70 characters
Dim dvrTest As DetailsViewRowCollection = DetailsView1.Rows
Dim TitleTB As TextBox = dvrTest.Item(0).Cells(1).Controls(0)
TitleTB.Attributes.Add("onkeydown", "isMaxLen(this)")
TitleTB.Attributes.Add("maxlength", "70")
Dim myDDL As DropDownList = DetailsView1.FindControl("reqCategoryDropDown")
''Perform dropdown list population operations
If Page.IsPostBack = False Then
Dim ticket_ID As String = getDataKey(DetailsView1)
''Fetch Category ID
Dim sqlText As String = "SELECT TS_REQCATEGORY FROM USR_ITFAC WHERE (TS_ID = " + ticket_ID + ") "
Dim reqDataReader As SqlDataReader = GetDataReader(sqlText)
reqDataReader.Read()
Dim category_ID As String = reqDataReader(0)
''Fetch Category name using the categoryID and set as selected value in dropdown list
sqlText = "SELECT TS_NAME FROM TS_SELECTIONS WHERE (TS_ID = " + category_ID + ") "
reqDataReader = GetDataReader(sqlText)
reqDataReader.Read()
category_Name = reqDataReader(0)
myDDL.DataBind()
End If
End Sub
Protected Sub DDL_DataBound(ByVal sender As Object, ByVal e As System.EventArgs)
If Page.IsPostBack = False Then
Dim myDDL As DropDownList = DetailsView1.FindControl("reqCategoryDropDown")
myDDL.Items.FindByValue(category_Name).Selected = True
End If
End Sub
答案 0 :(得分：2)
为安全起见，您可能需要点击DetailsView_DataBound，并将选择代码放在那里。我想也许数据源控件再次绑定并消除你的选择......