ASP.NET GridView删除按钮触发Object Reference异常问题求助

判断完全正确，触发RowDeleting事件时点击的是删除按钮，并未触发行选择逻辑，因此EduGrid.SelectedRow为null，访问其属性就会抛出空对象引用异常。同时原代码的列索引取值也存在错误，前两列是操作按钮，degree字段对应的单元格索引不是1。

直接通过事件参数的RowIndex属性获取当前触发删除操作的行，调整代码如下：

protected void EduGrid_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
    // 用e.RowIndex获取当前删除的行，不要用SelectedRow
    GridViewRow row = EduGrid.Rows[e.RowIndex];
    conn = new SqlConnection(connString);
    string query = "DELETE FROM [Edu Info] WHERE cnic = @cnic AND degree = @degree";
    sqlcmd = new SqlCommand(query, conn);
    sqlcmd.Parameters.AddWithValue("@cnic", lblID.Text);
    // 前两列是选择、删除按钮，degree对应第3个单元格，索引为2
    sqlcmd.Parameters.AddWithValue("@degree", row.Cells[2].Text.Trim());

    try
    {
        conn.Open();
        sqlcmd.ExecuteNonQuery();
        lblInfo.Text = "Record deleted successfully.";
        lblInfo.Visible = true;
        Get_Edu();
    }
    catch (Exception ex)
    {
        lblInfo.Text = "An error occurred. Please contact the administrator.";
        lblInfo.Visible = true;
    }
    finally
    {
        conn.Close();
        conn.Dispose();
        SqlConnection.ClearAllPools();
    }
}

为避免后续调整列顺序导致索引取值错误，建议使用GridView的DataKeyNames属性存储业务主键字段，无需读取单元格文本：

1. 前端GridView标签添加DataKeyNames属性：

<asp:GridView ID="EduGrid" 
    CssClass="edugrid table table-striped table-hover table-borderless" 
    runat="server" 
    AutoGenerateColumns="False" 
    GridLines="None" 
    OnRowDeleted="EduGrid_RowDeleted" 
    OnRowDeleting="EduGrid_RowDeleting"
    DataKeyNames="degree"> <!-- 新增这行，把需要用到的字段加入数据键 -->
    <!-- 其他原有内容保持不变 -->
</asp:GridView>

2. 后端直接从数据键中取值：

// 无需读取单元格，直接从DataKeys取degree值
string degree = EduGrid.DataKeys[e.RowIndex]["degree"].ToString().Trim();
sqlcmd.Parameters.AddWithValue("@degree", degree);

内容的提问来源于stack exchange，提问作者Atif Ali