Question

请考虑我在调试模式中获得的注释中的值：

protected void FilesGrid_SelectedIndexChanged(object sender, EventArgs e)
{
    int selected = FilesGrid.SelectedIndex; // selected = 2
    FilesGrid.DataBind();  //added after feedback in comments. it makes no change
    int count = FilesGrid.Rows.Count; // count = 0
    GridViewRow row = FilesGrid.Rows[selected]; // row = null
    GridViewRow row0 = FilesGrid.Rows[0]; // row = null
}

在调查为什么SelectedValue在此事件处理程序中为null时，我来到此代码（DataKeyNames参数已设置为肯定）。

有人可以解释一下这是怎么回事吗？

提前谢谢。

PS。这是我的aspx代码：

<asp:GridView ID="FilesGrid" runat="server" AutoGenerateColumns="False" 
    AutoGenerateSelectButton="True"  
    onselectedindexchanged="FilesGrid_SelectedIndexChanged" 
    style="margin-top: 0px" >
    <Columns>
        <asp:CommandField ShowDeleteButton="True" />
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="Length" DataFormatString="{0:N0}" 
            HeaderText="Size in Bytes" HtmlEncode="False" />
    </Columns>
</asp:GridView>

以下是我绑定数据的方式：

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        string [] dd = {"FullName"};
        FilesGrid.DataKeyNames = dd;

        string appPath = Request.PhysicalApplicationPath; 
        DirectoryInfo dirInfo = new DirectoryInfo(appPath); 
        FileInfo[] files = dirInfo.GetFiles();
        FilesGrid.DataSource = files;
        FilesGrid.DataBind();            } 
}

Answer 1

Y复制粘贴你的代码，删除FilesGrid_SelectedIndexChanged中的这行FilesGrid.DataBind（），我看到你没有发布的2个方法，这些方法不在你发布的onselectedindexchanging，onrowdeleting事件，评论的代码中它们来自aspx并查看它是否有效，或者如果事件没有做什么欺骗，那就是删除GridView中的行。

告诉我它是否有效

我做了这个

  protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            string[] dd = { "FullName" };
            FilesGrid.DataKeyNames = dd;

            string appPath = Request.PhysicalApplicationPath;
            DirectoryInfo dirInfo = new DirectoryInfo(appPath);
            FileInfo[] files = dirInfo.GetFiles();
            FilesGrid.DataSource = files;
            FilesGrid.DataBind();
        }
    }
    protected void FilesGrid_SelectedIndexChanged(object sender, EventArgs e)
    {
        int selected = FilesGrid.SelectedIndex; // selected = 2
        //FilesGrid.DataBind();  //added after feedback in comments. it makes no change
        int count = FilesGrid.Rows.Count; // count = 0
        GridViewRow row = FilesGrid.Rows[selected]; // row = null
        GridViewRow row0 = FilesGrid.Rows[0]; // row = null
    }
    protected void FilesGrid_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {

    }
    protected void FilesGrid_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
    {

    }

aspx代码。

<asp:ScriptManager ID="ScriptManager1" runat="server" EnableScriptGlobalization="true"
            AsyncPostBackTimeout="0" EnableScriptLocalization="true">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="upPanel" runat="server">
            <ContentTemplate>        
                <asp:GridView ID="FilesGrid" runat="server" AutoGenerateColumns="False" AutoGenerateSelectButton="True"
                    OnRowDeleting="FilesGrid_RowDeleting" OnSelectedIndexChanged="FilesGrid_SelectedIndexChanged"
                    Style="margin-top: 0px" OnSelectedIndexChanging="FilesGrid_SelectedIndexChanging">
                    <Columns>
                        <asp:CommandField ShowDeleteButton="True" />
                        <asp:BoundField DataField="Name" HeaderText="Name" />
                        <asp:BoundField DataField="Length" DataFormatString="{0:N0}" HeaderText="Size in Bytes"
                            HtmlEncode="False" />
                    </Columns>
                </asp:GridView>
            </ContentTemplate>         
        </asp:UpdatePanel>

Answer 2

删除评论中反馈后添加的FilesGrid.DataBind(); //。它没有变化当我将该语句添加到我的代码中时，我收到错误。删除后请再试一次。如果不能正常工作，请分享

protected void FilesGrid_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)方法代码可能是该部分的错误

Answer 3

通过评论专栏// if (!Page.IsPostBack)解决了该问题。看起来数据源在回发期间以某种方式丢失。整个似乎是ViewState的本地错误，因为其他用户没有观察到这种行为。我特别感谢Tim Schmelter和naveen。

Answer 4

您可以将Page.IsPostBack保留在Page_Load中，我遇到了同样的问题，结果发现网格在我的情况下不在ViewState中。如果在控制器中使用Linq查询，则需要将此属性添加到网格中，以便正确刷新： <asp:Panel EnableViewState="True">

选择行时，所有GridView行都会消失

4 个答案: