当我将数据 table 对象发送到分页 Class 方法时出现错误消息 "The source contains no DataRows"

Question

我有一个带有 DataGrid.Every 的用户控件很好，因为用户控件中的 DataGride 分页功能 Class.I 决定将分页功能移动到 class instead.This 是我的代码

    {


    private static DataTable _dt ;
    private static TextBlock _PageInformation;
    private static ComboBox _NumberOfRecords;
    private static Button _btnPrev;
    private static Button _BtnFirst;
    private static Button _BtnNext;
    private static Button _BtnLast;
    internal static AssetsManagement equipmentManage
    {
        get { return equipmentMng; }
        set { equipmentMng = value; }
    }
    private static DataGrid _datagridObject;

    public static TextBlock PageInformation { get => _PageInformation; set => _PageInformation = value; }
    public static DataTable dt { get => _dt; set => _dt = value; }
    public static ComboBox NumberOfRecords { get => _NumberOfRecords; set => _NumberOfRecords = value; }
    public static DataGrid DatagridObject { get => _datagridObject; set => _datagridObject = value; }
    public static Button BtnPrev { get => _btnPrev; set => _btnPrev = value; }
    public static Button BtnFirst { get => _BtnFirst; set => _BtnFirst = value; }
    public static Button BtnNext { get => _BtnNext; set => _BtnNext = value; }
    public static Button BtnLast { get => _BtnLast; set => _BtnLast = value; }

    int pageIndex = 1;
    public static int numberOfRecPerPage;
    //To check the paging direction according to use selection.
    private enum PagingMode
    { First = 1, Next = 2, Previous = 3, Last = 4, PageCountChange = 5 };

    public Pagenation(DataGrid UCDatagrid,ComboBox NumberOfRecordsComboBox,TextBlock PageInfo,DataTable Data,Button Prev, Button First, Button Next, Button Last)
    {
        DatagridObject = UCDatagrid;

        dt = Data.Copy();
        if (Data == null)
        {
            MessageBox.Show(Data.Rows.Count.ToString());
        }
        PageInformation = PageInfo;
        NumberOfRecords = NumberOfRecordsComboBox;

        Prev = BtnPrev;
        First = BtnFirst;
        Next= BtnNext;
       Last= BtnLast;
        NumberOfRecordsComboBox.Items.Add("5");
        NumberOfRecordsComboBox.Items.Add("10");
        NumberOfRecordsComboBox.Items.Add("15");
        NumberOfRecordsComboBox.Items.Add("20");
        NumberOfRecordsComboBox.Items.Add("25");
        RefreshDataGrid(dt);
    }
    public  void BtnFirst_Click(object sender, RoutedEventArgs e)
    {
        Navigate((int)PagingMode.First);

    }
    public void BtnNext_Click()
    {
        Navigate((int)PagingMode.Next);

    }


    public void BtnPrev_Click(object sender, RoutedEventArgs e)
    {
        Navigate((int)PagingMode.Previous);

    }

    public void BtnLast_Click(object sender, RoutedEventArgs e)
    {
        Navigate((int)PagingMode.Last);

    }
    public void CbNumberOfRecords_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        Navigate((int)PagingMode.PageCountChange);
    }

    private void Navigate(int mode)
    {
        int count;
        switch (mode)
        {
            case (int)PagingMode.Next:
                BtnPrev.IsEnabled = true;
                BtnFirst.IsEnabled = true;
                if (dt.Rows.Count >= (pageIndex * numberOfRecPerPage))
                {
                    if (dt.AsEnumerable().Skip(pageIndex *
                    numberOfRecPerPage).Take(numberOfRecPerPage).Count() == 0)
                    {
                        DatagridObject.ItemsSource = null;
                        DatagridObject.ItemsSource = dt.Rows.Count <= 0 ? null : dt.AsEnumerable().Skip((pageIndex *
                        numberOfRecPerPage) - numberOfRecPerPage).Take(numberOfRecPerPage).CopyToDataTable().DefaultView;
                        count = (pageIndex * numberOfRecPerPage) +
                        (dt.AsEnumerable().Skip(pageIndex *
                        numberOfRecPerPage).Take(numberOfRecPerPage)).Count();
                    }
                    else
                    {
                        DatagridObject.ItemsSource = null;
                        DatagridObject.ItemsSource = dt.Rows.Count <= 0 ? null : dt.AsEnumerable().Skip(pageIndex *
                        numberOfRecPerPage).Take(numberOfRecPerPage).CopyToDataTable().DefaultView;
                        count = (pageIndex * numberOfRecPerPage) +
                        (dt.AsEnumerable().Skip(pageIndex * numberOfRecPerPage).Take(numberOfRecPerPage)).Count();
                        pageIndex++;
                    }

                    PageInformation.Text = count + " of " + dt.Rows.Count;
                }

                else
                {
                    BtnNext.IsEnabled = false;
                    BtnLast.IsEnabled = false;
                }

                break;
            case (int)PagingMode.Previous:
                BtnNext.IsEnabled = true;
                BtnLast.IsEnabled = true;
                if (pageIndex > 1)
                {
                    pageIndex -= 1;
                    DatagridObject.ItemsSource = null;
                    if (pageIndex == 1)
                    {
                        DatagridObject.ItemsSource = dt.Rows.Count <= 0 ? null : dt.AsEnumerable().Take(numberOfRecPerPage).CopyToDataTable().DefaultView;
                        count = dt.AsEnumerable().Take(numberOfRecPerPage).Count();
                        PageInformation.Text = count + " of " + dt.Rows.Count;
                    }
                    else
                    {
                        DatagridObject.ItemsSource = dt.Rows.Count <= 0 ? null : dt.AsEnumerable().Skip
                        (pageIndex * numberOfRecPerPage).Take(numberOfRecPerPage).CopyToDataTable().DefaultView;
                        count = Math.Min(pageIndex * numberOfRecPerPage, dt.Rows.Count);
                        PageInformation.Text = count + " of " + dt.Rows.Count;

                    }
                }
                else
                {
                    BtnPrev.IsEnabled = false;
                    BtnFirst.IsEnabled = false;
                }
                break;

            case (int)PagingMode.First:
                pageIndex = 2;
                Navigate((int)PagingMode.Previous);
                break;
            case (int)PagingMode.Last:
                pageIndex = (dt.Rows.Count / numberOfRecPerPage);
                Navigate((int)PagingMode.Next);
                break;

            case (int)PagingMode.PageCountChange:
                numberOfRecPerPage = Convert.ToInt32(NumberOfRecords.SelectedItem);
                DatagridObject.ItemsSource = null;
                DatagridObject.ItemsSource = dt.Rows.Count <= 0 ? null : dt.AsEnumerable().Take(numberOfRecPerPage).CopyToDataTable().DefaultView;
                count = (dt.AsEnumerable().Take(numberOfRecPerPage)).Count();
                PageInformation.Text = count + " of " + dt.Rows.Count;
                BtnNext.IsEnabled = true;
                BtnLast.IsEnabled = true;
                BtnPrev.IsEnabled = true;
                BtnFirst.IsEnabled = true;
                break;
        }
    }
    public static void RefreshDataGrid(DataTable dte)
    {
        MessageBox.Show(dte.Rows.Count.ToString());

        dt = dte.Copy();
        MessageBox.Show(dt.Rows.Count.ToString());

        DatagridObject.ItemsSource = null;
        DatagridObject.ItemsSource = dt.AsEnumerable().Take(numberOfRecPerPage).CopyToDataTable().DefaultView;

        int count = dt.AsEnumerable().Take(numberOfRecPerPage).Count();
        PageInformation.Text = count + " of " + dt.Rows.Count;

    }

}}

并且在 UserControl 的 Class 中，我使用构造函数实例化了一个分页 Class 的对象，该构造函数采用了分页所需的所有变量。

 public PartsUC()
    {
        InitializeComponent();
        PartsDataTable = PartMng.GetAllEquipments();
        MessageBox.Show(PartsDataTable.Rows.Count.ToString());
        PageInformation = lblpageInformation;
         Partsdatagrid = this.PartsDataGrid;
        CbNumberOfRecords = this.cbNumberOfRecords;//the interface XAMAL Combobox

       Pagenation pagenation = new Pagenation(Partsdatagrid, cbNumberOfRecords, PageInformation, PartsDataTable, btnPrev, btnFirst, btnNext, btnLast);
        //Pagenation.RefreshDataGrid(PartsDataTable);}

问题是我仍然收到此错误消息！

The source contains no DataRows and the error points to the refreshDataGrid method in this line

DatagridObject.ItemsSource = dt.AsEnumerable().Take(numberOfRecPerPage).CopyToDataTable().DefaultView;

请注意，函数 refreshDataGrid 中的消息框显示我有 50 行。

Answer 1

已解决，导致错误的是函数 Take()，因为它从组合框中获取数字，让您选择要 display.I 放置固定数字的行数，它起作用了。

DatagridObject.ItemsSource = dt.AsEnumerable().Take(15).CopyToDataTable().DefaultView;

当我将数据 table 对象发送到分页 Class 方法时出现错误消息 "The source contains no DataRows"

Error messege "The source contains no DataRows" when i sent a data table object to a pagenation Class method

c#

wpf

datatable

datagrid

itemsource