当数据表中不存在列但在itemtemplate处绑定时绑定gridview答案

【问题标题】：Bind gridview when column not exists in datatable but binding at itemtemplate当数据表中不存在列但在itemtemplate处绑定时绑定gridview
【发布时间】：2013-05-03 05:04:18
【问题描述】：

我有一个dataset，我正在旋转它，然后绑定到一个网格视图。当所有itemtemplates 值都存在于透视表中时，它工作正常，但如果透视表中不存在任何列，那么在绑定gridview 时，我会出错。请帮助我，如果任何列不存在，我将如何在网格视图中处理它，但我将其绑定到网格视图itemtemplate。下面是我的网格视图代码。

                    <asp:GridView ID="gvCoreUtilization" runat="server" BackColor="White" BorderColor="#cEcFcE"
                    BorderStyle="Solid" BorderWidth="1px" CellPadding="4" ForeColor="Black" OnRowCreated="grdPivot3_RowCreated"
                    AutoGenerateColumns="false" OnRowDataBound="grdCoreUtilization_RowDataBound">
                    <RowStyle BackColor="#F7F7DE" />
                    <FooterStyle BackColor="#CCCC99" />
                    <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
                    <SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
                    <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
                    <AlternatingRowStyle BackColor="White" />
                    <Columns>
                        <asp:TemplateField>
                            <ItemTemplate>
                                <asp:Label ID="lblRoleID" Text='<%#Eval("RoleId") %>' runat="server" Visible="false"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                SupervisorName
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblSupervisorName" Text='<%#Eval("SupervisorName") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                UserECode
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblUserECode" Text='<%#Eval("UserECode") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                UserName
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblUserName" Text='<%#Eval("UserName") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Designation
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblDesignation" Text='<%#Eval("Designation") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                L & D Training%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblLDTraining" Text='<%#Eval("L & D Training%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Non Production%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblNonProduction" Text='<%#Eval("Non Production%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Process Support%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblProcessSupport" Text='<%#Eval("Process Support%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Process Training%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblProcessTraining" Text='<%#Eval("Process Training%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Production%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblProduction" Text='<%#Eval("Production%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                System Downtime%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblSystemDowntime" Text='<%#Eval("System Downtime%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField>
                            <HeaderTemplate>
                                Grand Total%
                            </HeaderTemplate>
                            <ItemTemplate>
                                <asp:Label ID="lblGrandTotal" Text='<%#Eval("Grand Total%") %>' runat="server"></asp:Label>
                            </ItemTemplate>
                        </asp:TemplateField>
                    </Columns>
                </asp:GridView>

实际上 "L & D Training%","Non Production%","Process Support%","Process Training%","Production%","System Downtime%","Grand Total%" 是我绑定到 itemtemplate 的旋转列。对于这些列中的一些用户来说不存在，并且在绑定网格时出现错误。

下面是我正在执行枢轴的 Pivot 类的代码：-

private DataTable _SourceTable = new DataTable();
    private IEnumerable<DataRow> _Source = new List<DataRow>();

    public Pivot(DataTable SourceTable)
    {
        _SourceTable = SourceTable;
        _Source = SourceTable.Rows.Cast<DataRow>();
    }

    public DataTable PivotData(string DataField, AggregateFunction Aggregate, string[] RowFields, string[] ColumnFields)
    {
        DataTable dt = new DataTable();
        string Separator = ".";
        var RowList = _SourceTable.DefaultView.ToTable(true, RowFields).AsEnumerable().ToList();
        for (int index = RowFields.Count() - 1; index >= 0; index--)
            RowList = RowList.OrderBy(x => x.Field<object>(RowFields[index])).ToList();
        // Gets the list of columns .(dot) separated.
        var ColList = (from x in _SourceTable.AsEnumerable()
                       select new
                       {
                           Name = ColumnFields.Select(n => x.Field<object>(n))
                               .Aggregate((a, b) => a += Separator + b.ToString())
                       })
                           .Distinct()
                           .OrderBy(m => m.Name);

        //dt.Columns.Add(RowFields);
        foreach (string s in RowFields)
            dt.Columns.Add(s);

        foreach (var col in ColList)
            dt.Columns.Add(col.Name.ToString());  // Cretes the result columns.//

        foreach (var RowName in RowList)
        {
            DataRow row = dt.NewRow();
            string strFilter = string.Empty;

            foreach (string Field in RowFields)
            {
                row[Field] = RowName[Field];
                strFilter += " and " + Field + " = '" + RowName[Field].ToString() + "'";
            }
            strFilter = strFilter.Substring(5);

            foreach (var col in ColList)
            {
                string filter = strFilter;
                string[] strColValues = col.Name.ToString().Split(Separator.ToCharArray(), StringSplitOptions.None);
                for (int i = 0; i < ColumnFields.Length; i++)
                    filter += " and " + ColumnFields[i] + " = '" + strColValues[i] + "'";
                row[col.Name.ToString()] = GetData(filter, DataField, Aggregate);
            }
            dt.Rows.Add(row);
        }
        return dt;
    }

    public DataTable PivotAllocationData(string DataField, AggregateFunction Aggregate, string[] RowFields, string[] ColumnFields)
    {
        DataTable dt = new DataTable();
        string Separator = ".";
        var RowList = _SourceTable.DefaultView.ToTable(true, RowFields).AsEnumerable().ToList();
        for (int index = RowFields.Count() - 1; index >= 0; index--)
            RowList = RowList.OrderBy(x => x.Field<object>(RowFields[index])).ToList();
        // Gets the list of columns .(dot) separated.
        var ColList = (from x in _SourceTable.AsEnumerable()
                       select new
                       {
                           Name = ColumnFields.Select(n => x.Field<object>(n))
                               .Aggregate((a, b) => a += Separator + b.ToString())
                       })
                           .Distinct()
                           .OrderBy(m => m.Name);

        //dt.Columns.Add(RowFields);
        foreach (string s in RowFields)
            dt.Columns.Add(s);

        foreach (var col in ColList)
            dt.Columns.Add(col.Name.ToString());  // Cretes the result columns.//

        foreach (var RowName in RowList)
        {
            DataRow row = dt.NewRow();
            string strFilter = string.Empty;

            foreach (string Field in RowFields)
            {
                row[Field] = RowName[Field];
                strFilter += " and " + Field + " = '" + RowName[Field].ToString() + "'";
            }
            strFilter = strFilter.Substring(5);

            foreach (var col in ColList)
            {
                string filter = strFilter;
                string[] strColValues = col.Name.ToString().Split(Separator.ToCharArray(), StringSplitOptions.None);
                for (int i = 0; i < ColumnFields.Length; i++)
                    filter += " and " + ColumnFields[i] + " = '" + strColValues[i] + "'";
                row[col.Name.ToString()] = GetAllocationData(filter, DataField, Aggregate);
            }
            dt.Rows.Add(row);
        }
        return dt;
    }
    /// <summary>
    /// Retrives the data for matching RowField value and ColumnFields values with Aggregate function applied on them.
    /// </summary>
    /// <param name="Filter">DataTable Filter condition as a string</param>
    /// <param name="DataField">The column name which needs to spread out in Data Part of the Pivoted table</param>
    /// <param name="Aggregate">Enumeration to determine which function to apply to aggregate the data</param>
    /// <returns></returns>
    private object GetData(string Filter, string DataField, AggregateFunction Aggregate)
    {
        try
        {
            DataRow[] FilteredRows = _SourceTable.Select(Filter);
            object[] objList = FilteredRows.Select(x => x.Field<object>(DataField)).ToArray();

            switch (Aggregate)
            {
                case AggregateFunction.Average:
                    return GetAverage(objList);
                case AggregateFunction.Count:
                    return objList.Count();
                case AggregateFunction.Exists:
                    return (objList.Count() == 0) ? "False" : "True";
                case AggregateFunction.First:
                    return GetFirst(objList);
                case AggregateFunction.Last:
                    return GetLast(objList);
                case AggregateFunction.Max:
                    return GetMax(objList);
                case AggregateFunction.Min:
                    return GetMin(objList);
                case AggregateFunction.Sum:
                    return GetSum(objList);
                default:
                    return null;
            }
        }
        catch (Exception ex)
        {
            return "#Error";
        }
    }

    /// <summary>
    /// Retrives the data for matching RowField value and ColumnFields values with Aggregate function applied on them.
    /// </summary>
    /// <param name="Filter">DataTable Filter condition as a string</param>
    /// <param name="DataField">The column name which needs to spread out in Data Part of the Pivoted table</param>
    /// <param name="Aggregate">Enumeration to determine which function to apply to aggregate the data</param>
    /// <returns></returns>
    private object GetAllocationData(string Filter, string DataField, AggregateFunction Aggregate)
    {
        try
        {
            DataRow[] FilteredRows = _SourceTable.Select(Filter);
            object[] objList = FilteredRows.Select(x => x.Field<object>(DataField)).ToArray();

            switch (Aggregate)
            {
                case AggregateFunction.Average:
                    return GetAverage(objList);
                case AggregateFunction.Count:
                    return objList.Count();
                case AggregateFunction.Exists:
                    return (objList.Count() == 0) ? "False" : "True";
                case AggregateFunction.First:
                    return GetFirst(objList);
                case AggregateFunction.Last:
                    return GetLast(objList);
                case AggregateFunction.Max:
                    return GetMax(objList);
                case AggregateFunction.Min:
                    return GetMin(objList);
                case AggregateFunction.Sum:
                    return GetAllocationSum(objList);
                default:
                    return null;
            }
        }
        catch (Exception ex)
        {
            return "#Error";
        }
    }

    private object GetAverage(object[] objList)
    {
        return objList.Count() == 0 ? null : (object)(Convert.ToDecimal(GetSum(objList)) / objList.Count());
    }
    private object GetSum(object[] objList)
    {
        return objList.Count() == 0 ? null : (object)(objList.Aggregate(new decimal(), (x, y) => x += Convert.ToDecimal(y)) + "%");
    }
    private object GetAllocationSum(object[] objList)
    {
        return objList.Count() == 0 ? null : (object)(objList.Aggregate(new decimal(), (x, y) => x += Convert.ToDecimal(y)));
    }
    private object GetFirst(object[] objList)
    {
        return (objList.Count() == 0) ? null : objList.First();
    }
    private object GetLast(object[] objList)
    {
        return (objList.Count() == 0) ? null : objList.Last();
    }
    private object GetMax(object[] objList)
    {
        return (objList.Count() == 0) ? null : objList.Max();
    }
    private object GetMin(object[] objList)
    {
        return (objList.Count() == 0) ? null : objList.Min();
    }


public enum AggregateFunction

{ 计数 = 1，总和 = 2，第一个 = 3，最后 = 4，平均值 = 5, 最大值 = 6，最小值 = 7，存在 = 8 }

【问题讨论】：

是否有任何主键会出现在每个场景中？
不是，实际上是 "L & D Training%","Non Production%","Process Support%","Process Training%","Production%","System Downtime%","Grand Total%" 是我绑定到 itemtemplate 的透视列。对于某些用户，这些列中的一些不存在，并且在绑定网格时出现错误。\
在你的数据库查询中试试ifnull(columnname,'') as abc这里的列名是你的表列名，''基本上是将此列分配给默认值，如果它返回null并且abc是列的别名。希望你明白,,试试...
这意味着您的数据在excel文件中？？如果是，那么您如何查询它？使用 oledb 还是别的什么？请提供完整的详细信息，因为实际实施将取决于所使用的实际数据库层。
更新了我的问题并提供了我用来使我的数据表在数据透视表中的代码。

标签： c# asp.net

【解决方案1】：

由于您没有提供实际使用的数据库。您可以应用以下技巧。问题是您将需要创建一个包装类来提取您拥有的任何数据，然后将数据格式化为网格正在使用的明确定义的模式。

例如。假设您在一个表中有 3 列，但另一列可以包含 3，依此类推。由于您的网格视图外观相同，因此创建一个包含网格视图所有行的数据表。创建一个函数，提取所有数据并用可用数据填充此数据表，不可用数据将由 null 或空白值填充。

这样你可以缓解异常被抛出的问题。将可变长度表转换为固定长度数据表的函数的实际实现将取决于用于创建这些可变长度数据表的实际逻辑以及它们如何相互映射。

【讨论】：