GridView 在回发期间丢失列内容

发布于 2025-01-07 22:55:33 字数 2557 浏览 1 评论 0 原文

我对回发之间的 GridView 行为有疑问。

真正的问题来自于我在 column[0] 的标记中定义的 TemplateField 以及子 CheckBox 控件。第一次和第二次搜索执行时一切正常。然而，在第二次执行和之后导致回发的任何事情之间的某个时刻，我丢失了 TemplateField 的内容。

它只是列的内容，而不是整个列本身被删除。 TemplateField 存在于源中，并在表的位置 0 处显示格式化列。

代码：

protected void ExecuteSearch(object sender, EventArgs e)
{
    if (lb_SelectedFields.Items.Count == 0) { return; } //if no selected fields

    //Generates custom SQL query based on user inputs and column Selections
    BuildQuery(); // sets txbSqlText.Text = to the SQL string

    DataTable Table = SqlAdapter.Select(new System.Data.SqlClient.SqlCommand(txbSqlText.Text));

    for (int i = gv_SearchResults.Columns.Count - 1; i > 0; i--) 
    { gv_SearchResults.Columns.RemoveAt(i); } //removes all the columns except[0]

    foreach (ListItem Item in lb_SelectedFields.Items) //adds all the user defined columns
    {
        //Column object that is able to find the column definition
        Column Col = ColumnsBasedOnFocus.FindColumName(Item.Value); 

        if (Col.Type == "HyperLink") { gv_SearchResults.Columns.Add(CreateHyperLinkField(Col)); }
        else { gv_SearchResults.Columns.Add(CreateBoundColumn(Col, true)); } //true is if the column is visable
    }

    gv_SearchResults.DataSource = Table;
    gv_SearchResults.DataBind();
}

ASP.NET：

<asp:GridView ID="gv_SearchResults" runat="server" GridLines="None" CellSpacing="0"
    CellPadding="0" AutoGenerateColumns="false" CssClass="TABLE_LIGHTBLUE" Width="100%">
    <HeaderStyle CssClass="TABLE_LIGHTBLUE_HEADERROW" />
    <Columns>
        <asp:TemplateField ItemStyle-Width="30" ItemStyle-Wrap="false">
            <HeaderTemplate>
                <center>
                    <asp:Button ID="btn_SelectAll" runat="server" OnClick="SelectAll" Text="All" CssClass="TEXT_SMALL" />
                    <asp:CheckBox ID="chk_Placeholder" runat="server" Visible="false" /></center>
            </HeaderTemplate>
            <ItemTemplate>
                <center>
                    <asp:CheckBox ID="chk_Select" runat="server" Visible="true" />
                    <asp:Label ID="lbl_AssetGID" runat="server" Visible="false" Text='<%# Bind("i_GID") %>' /></center>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

原文

I am having an issue with the behavior of a GridView between post backs.

The real problem comes from a TemplateField I define in the markup at column[0] with a child CheckBox control. Things work fine for the first, and second search executions. However, at some point between the second execution and anything that causes a post back there after, I lose the contents of the TemplateField.

Its only the the contents of the column and not the whole column itself that gets removed. The TemplateField is present in the source and shows a formated column at position 0 of the table.

CODE:

protected void ExecuteSearch(object sender, EventArgs e)
{
    if (lb_SelectedFields.Items.Count == 0) { return; } //if no selected fields

    //Generates custom SQL query based on user inputs and column Selections
    BuildQuery(); // sets txbSqlText.Text = to the SQL string

    DataTable Table = SqlAdapter.Select(new System.Data.SqlClient.SqlCommand(txbSqlText.Text));

    for (int i = gv_SearchResults.Columns.Count - 1; i > 0; i--) 
    { gv_SearchResults.Columns.RemoveAt(i); } //removes all the columns except[0]

    foreach (ListItem Item in lb_SelectedFields.Items) //adds all the user defined columns
    {
        //Column object that is able to find the column definition
        Column Col = ColumnsBasedOnFocus.FindColumName(Item.Value); 

        if (Col.Type == "HyperLink") { gv_SearchResults.Columns.Add(CreateHyperLinkField(Col)); }
        else { gv_SearchResults.Columns.Add(CreateBoundColumn(Col, true)); } //true is if the column is visable
    }

    gv_SearchResults.DataSource = Table;
    gv_SearchResults.DataBind();
}

ASP.NET:

<asp:GridView ID="gv_SearchResults" runat="server" GridLines="None" CellSpacing="0"
    CellPadding="0" AutoGenerateColumns="false" CssClass="TABLE_LIGHTBLUE" Width="100%">
    <HeaderStyle CssClass="TABLE_LIGHTBLUE_HEADERROW" />
    <Columns>
        <asp:TemplateField ItemStyle-Width="30" ItemStyle-Wrap="false">
            <HeaderTemplate>
                <center>
                    <asp:Button ID="btn_SelectAll" runat="server" OnClick="SelectAll" Text="All" CssClass="TEXT_SMALL" />
                    <asp:CheckBox ID="chk_Placeholder" runat="server" Visible="false" /></center>
            </HeaderTemplate>
            <ItemTemplate>
                <center>
                    <asp:CheckBox ID="chk_Select" runat="server" Visible="true" />
                    <asp:Label ID="lbl_AssetGID" runat="server" Visible="false" Text='<%# Bind("i_GID") %>' /></center>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

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离去的眼神 2025-01-14 22:55:33

找到一个描述类似情况的链接。

https://connect.microsoft.com/VisualStudio/feedback/details/104994/templatefield-in-a-gridview-doesnt-have-its-viewstate-restored-when-boundfields-are-inserted#详细信息

它们描述了 ASP.Net 代码中的一个错误，该错误无法使用动态生成的网格视图中的模板字段正确管理视图状态。

回复收藏 0 原文

烟若柳尘 2025-01-14 22:55:33

基本上，TemplateFields 无法从 ViewState 正确恢复，并且如果您以编程方式修改 ASPX 声明的列，它也无法从声明创建它们。
我可以使用的唯一解决方案是创建一个从 TemplateField 派生的新类，该类在构造函数中将 ItemTemplate 设置为 ITemplate 派生类，这意味着必须以编程方式而不是声明方式定义模板。
您还可以在每次回发时重新绑定 gridview，但这是它自己的蠕虫。