SfDataGrid and SfDataPage OnDemandLoading first page is not displayed

Question

When loading a page, the first page is not displayed, switching to the second page loads the data



public partial class OrdersListPage : ContentPage
{
    private OrdersListViewModel vm;
    private SfDataGrid dataGrid;
    private SfDataPager dataPager;
    public OrdersListPage()
    {
        vm = ServiceHelper.GetService<OrdersListViewModel>();
        BindingContext = vm;


        var grid = new Grid
        {
            RowDefinitions = new RowDefinitionCollection
            {
                new RowDefinition(70),
                new RowDefinition(Star),
                new RowDefinition(70)
            }
        };


        dataGrid = new SfDataGrid
        {
            AutoGenerateColumnsMode = AutoGenerateColumnsMode.None,
            RowHeight = 50,
            HorizontalOptions = LayoutOptions.Fill,
            ColumnWidthMode = ColumnWidthMode.Fill,
            Columns = new ColumnCollection
            {
                new DataGridTextColumn
                {
                    MappingName = "OrderId",
                    HeaderText = "№ Заказа",
                    MinimumWidth = 150
                },
                new DataGridTextColumn
                {
                    MappingName = "Status",
                    HeaderText = "Статус",
                    MinimumWidth = 200
                },
                new DataGridTextColumn
                {
                    MappingName = "OrderChanel",
                    HeaderText = "Источник",
                    MinimumWidth = 200
                },
                new DataGridTextColumn
                {
                    MappingName = "PaymentStatus",
                    HeaderText = "Оплата",
                    MinimumWidth = 200
                },
                new DataGridTextColumn
                {
                    MappingName = "DeliveryStatus",
                    HeaderText = "Доставка",
                    MinimumWidth = 200
                },
                new DataGridNumericColumn
                {
                    MappingName = "OrderTotal",
                    HeaderText = "Сумма",
                    MinimumWidth = 200,
                    Format = "#"
                },
                new DataGridCheckBoxColumn
                {
                    MappingName = "CheckIn",
                    HeaderText = "Чек",
                    MinimumWidth = 200
                },
                new DataGridTextColumn
                {
                    MappingName = "CreateDate",
                    HeaderText = "Дата",
                    MinimumWidth = 250
                }
            }
        };


        dataGrid.Row(1);


        dataPager = new SfDataPager
        {
            PageSize = 20,
            PageCount = 10,
            NumericButtonCount = 10,
            UseOnDemandPaging = true
        };
        dataPager.Row(2);


        dataPager.OnDemandLoading += dataPager_OnDemandLoading;


        dataGrid.SetBinding(SfDataGrid.ItemsSourceProperty, new Binding(){Path = "PagedSource", Source = dataPager, Mode = BindingMode.TwoWay});


        grid.Children.Add(dataPager);


        grid.Children.Add(dataGrid);


        Content = grid;
    }


    private async void dataPager_OnDemandLoading(object? sender, OnDemandLoadingEventArgs e)
    {
        var sourse = await vm.LoadOrders();
        dataPager.LoadDynamicItems(e.StartIndex,  sourse.Skip(e.StartIndex).Take(e.PageSize));
        (dataPager.PagedSource as PagedCollectionView).ResetCache();
    }
}

Nirmalkumar Yuvaraj · Answer

Hi Igor, Based on the provided
information, we conducted tests using a simple sample to replicate the reported
issues. However, we were unable to reproduce the issues as described. In our
sample, we set the DataSource using onDemandPaging, and the
DataGrid is functioning properly. The first page loads with data.We tested this scenario
using the attached sample, and it worked correctly without any issues. If you
are still encountering the problem, we kindly request that you modify the
attached sample to reproduce the issue and provide additional details. This
will greatly assist us in further investigating the issue and providing an
appropriate solution as quickly as possible.Regards,NirmalkumarAttachment: SfDataGridSample_7db7b751.zip

Igor · Answer

Hi!I am getting data asynchronously from the server and the first page is not displayed!If I remove the asynchrony, at all stages of data retrieval, the data is displayed, but it causes a noticeable slowdown in the application.

Nirmalkumar Yuvaraj · Answer

Hi Igor, Based on the information
provided, we have prepared a sample that asynchronously sets the datasource to
the datapager. However, while testing, both the datapager and datagrid seem to
be working fine. I have shared the sample with you for your reference. If you
are still encountering the problem, we kindly request that you modify the
attached sample to reproduce the issue and provide additional details. This
will greatly assist us in further investigating the issue and providing an
appropriate solution as quickly as possible.Regards,NirmalkumarAttachment: SfDataGridSample_1667a2fd.zip

Igor · Answer

Hi!Your example failed to run, I changed the path to the file, but still got a white screenI have attached my exampleRunning under macos systemAttachment: AppStockAndOrdersMAUI_4ada5dac.zip

Nirmalkumar Yuvaraj · Answer

Hi Igor, Based on the information provided in the note of the
following link , it is not advisable to set the value for the source in the event itself.
Please set the value of the source elsewhere and check if the issue persists.Regards,Nirmalkumar.

Igor · Answer

HiPagination is not working with asynchrony, I have called in different places the method to get data. The last option I sent, I received the data in an event to make sure it had time to loadIf you receive data in the ViewModel constructor, they do not have time to load, the pagination event is triggered and there is an empty collection there

Nirmalkumar Yuvaraj · Answer

Hi Igor,

Based on the
information provided, the issue you are experiencing is related to the view not
refreshing. After loading the data in onDemandPaging, you can use
view.Refresh() to refresh the view. We have attached a code snippet for your
reference.

Code snippet:

private async void
  dataPager_OnDemandLoading(object? sender, OnDemandLoadingEventArgs e)
  {
      var source = await vm.LoadOrders();
      dataPager.LoadDynamicItems(e.StartIndex,
  source.Skip(e.StartIndex).Take(e.PageSize));
      dataGrid.View!.Refresh();
  }

If this post is
helpful, please consider Accepting it as the solution so that other members can
locate it more quickly.

Regards,Nirmalkumar.

Igor · Answer

Hi!This helps with the display

Nirmalkumar Yuvaraj · Answer

Hi Igor, We hope the provided
solution resolves the issue on your end. Please get back to us if you need
further assistance. Regards,Nirmalkumar.