GridView1.SelectedIndex索引越界异常问题求助

• 在GridView1_SelectedIndexChanged函数内可正常获取选中行，但在其他函数中访问GridView1.SelectedRow会触发索引越界异常
• 点击GridView的选择按钮后，整个GridView会消失
• 尝试重新绑定GridView也无法解决上述问题

后端代码 #

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        ' Only add the event handler on initial page load
        AddHandler GridView1.SelectedIndexChanged, AddressOf GridView1_SelectedIndexChanged
        GridView1.DataBind()
    End If
End Sub

'Protected Sub GridView1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles GridView1.SelectedIndexChanged
'    Try
'        If GridView1.SelectedIndex <> -1 Then
'            UpdateButtonVisibility()
'            Dim itemSelected As GridViewRow = GridView1.SelectedRow
'            Dim acoo As String = itemSelected.Cells(1).Text

'            Dim conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ExtranetConnectionString").ConnectionString)
'            Dim query As String = "Select InvoiceAttach FROM TblInvoice WHERE CertificateId=@acoo"

'            Using sqlCmd As New SqlCommand(query, conn)
'                sqlCmd.Parameters.Add(New SqlParameter("acoo", acoo))
'                conn.Open()

'                Dim reader As SqlDataReader = sqlCmd.ExecuteReader()

'                If reader.HasRows Then
'                    reader.Read()
'                    'url = "/Files/" & reader("InvoiceAttach")
'                    url = reader("InvoiceAttach") & ""
'                    Dim s As String = "window.open('" & url + "', 'popup_window', 'width=500,height=800,left=100,top=100,resizable=yes');"
'                    ClientScript.RegisterStartupScript(Me.GetType(), "script", s, True)

'                End If
'              
'            End Using
'        End If
'    Catch ex As Exception
'        MsgBox(ex.Message)
'    End Try
'    GridView1.DataBind()
'End Sub

前端代码 #

<asp:GridView ID="GridView1" runat="server" CssClass="table" EnableViewState="true" AutoGenerateColumns="False" AutoPostBack="True" DataSourceID="SqlDataSource1" AllowPaging="True" AllowSorting="True" CellPadding="4" ForeColor="#333333" GridLines="None">
    <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
    <Columns>
        <asp:CommandField ShowSelectButton="True" />
        <asp:BoundField DataField="Acoo" HeaderText="Acoo" InsertVisible="False" ReadOnly="True" SortExpression="Acoo" />
        <asp:BoundField DataField="Tp" HeaderText="Tp" SortExpression="Tp" />
        <asp:BoundField DataField="Idno" HeaderText="Idno" SortExpression="Idno" />
        <asp:BoundField DataField="Status" HeaderText="Status" SortExpression="Status" />
        <asp:BoundField DataField="invoicenumber" HeaderText="invoicenumber" SortExpression="invoicenumber" />
        <asp:BoundField DataField="invoicedate" HeaderText="invoicedate" SortExpression="invoicedate" />
    </Columns>
    <EditRowStyle BackColor="#999999" />
    <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
    <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
    <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
    <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
    <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
    <SortedAscendingCellStyle BackColor="#E9E7E2" />
    <SortedAscendingHeaderStyle BackColor="#506C8C" />
    <SortedDescendingCellStyle BackColor="#FFFDF8" />
    <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ExtranetConnectionString %>" SelectCommand="SELECT Acoo, Tp, Idno, Status, invoicenumber, invoicedate FROM TblACOO WHERE (Status = 4) AND (Tp = @Tp) AND (Idno = @Idno) ORDER BY invoicedate DESC">
    <SelectParameters>
        <asp:FormParameter FormField="type" Name="Tp" Type="Int32" />
        <asp:FormParameter FormField="idno" Name="Idno" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>

问题原因分析 #

1. GridView消失：SqlDataSource1使用FormParameter获取type和idno参数，PostBack时表单字段值可能丢失或未传递，导致查询无结果，GridView因无数据显示消失。
2. 索引越界异常：PostBack后GridView无数据但SelectedIndex状态仍保留，此时访问SelectedRow会因实际无行数据触发异常；同时Page_Load仅在首次加载绑定，PostBack时参数失效导致绑定也拿不到数据。

修复步骤 #

1. 确保PostBack时参数不丢失 #

将FormParameter替换为SessionParameter，先在首次加载时把表单值存入Session：

' Page_Load修改
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Session("Tp") = Request.Form("type")
        Session("Idno") = Request.Form("idno")
        GridView1.DataBind()
    End If
End Sub

<!-- SqlDataSource参数修改 -->
<SelectParameters>
    <asp:SessionParameter SessionField="Tp" Name="Tp" Type="Int32" />
    <asp:SessionParameter SessionField="Idno" Name="Idno" Type="Int32" />
</SelectParameters>

2. 移除重复事件绑定 #

GridView已通过Handles关键字绑定事件，无需手动AddHandler，修改Page_Load：

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    If Not IsPostBack Then
        ' 移除AddHandler代码
        GridView1.DataBind()
    End If
End Sub

3. 访问SelectedRow前做判断 #

在任何需要访问GridView1.SelectedRow的代码前，先检查数据是否存在：

If GridView1.Rows.Count > 0 AndAlso GridView1.SelectedIndex <> -1 Then
    Dim itemSelected As GridViewRow = GridView1.SelectedRow
    ' 后续业务逻辑
Else
    ' 处理无数据或未选中的情况
End If

4. 移除SelectedIndexChanged中的重复绑定 #

原注释代码最后调用的GridView1.DataBind()会导致选中状态丢失，建议删除该行，SqlDataSource绑定的GridView会自动维护状态。

内容的提问来源于stack exchange，提问作者CCIABML