How to: Create the Underlying Data Source (Drill-Down) in an Asynchronous Operation

• Jun 27, 2019
• 3 minutes to read

This example performs an asynchronous operation that creates a drill-down data source for the selected PivotGrid cell and gets the operation result - the underlying data source.

In this example, the PivotGrid control is bound to the LinqServerModeSource data source and operates in server mode.

The PivotGridControl.CellClick event handler calls the PivotGridControl.CreateDrillDownDataSourceAsync method to generate a drill-down data source for the selected cell. The method parameter specifies the number of records to return. The method also specifies the columns to add to the the data set.

The last item in the method’s parameter list is the AsyncCompletedHandler delegate. The delegate is executed when the operation is complete. The delegate’s result parameter is the AsyncOperationResult instance whose Value property contains the result of the operation.

The operation’s result is cast to the PivotDrillDownDataSource and the GridControl displays the underlying records in the auxiliary DrillDown form.

Note

The complete sample project How to Create the Underlying Data Source (Drill-Down) in an Asynchronous Operation is available in the DevExpress Examples repository.

C#

using DevExpress.XtraPivotGrid;
using System;
using System.Collections.Generic;

namespace XtraPivotGrid_CreateDrillDownDataSourceAsync {
    public partial class Form1 : DevExpress.XtraEditors.XtraForm
    {
        DrillDownForm dForm;
        public Form1()
        {
            InitializeComponent();
            this.Load += Form1_Load;
            pivotGridControl1.CellClick += pivotGridControl1_CellClick;
            // This line of code is generated by Data Source Configuration Wizard
            linqServerModeSource1.QueryableSource = new XtraPivotGrid_CreateDrillDownDataSourceAsync.DataClasses1DataContext().Invoices;
        }
        private void pivotGridControl1_CellClick(object sender, 
            DevExpress.XtraPivotGrid.PivotCellEventArgs e) {
            PivotGridControl pivot = sender as PivotGridControl;
            if (dForm.IsDisposed) LoadDrillDownForm();

            //Check whether an asynchronous operation is in progress.
            if (!pivot.IsAsyncInProgress)

                // Get the record set associated with the clicked cell.
                pivot.CreateDrillDownDataSourceAsync(e.ColumnIndex, e.RowIndex, 25, new List<string> { "ProductName","Quantity" }, result => {
                    // The 'result' parameter of the delegate returns an AsyncOperationResult instance.
                    // The AsyncOperationResult.Value property contains a record set.
                    dForm.DataSource = (PivotDrillDownDataSource)result.Value;
                });
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            LoadDrillDownForm();
        }
        private void LoadDrillDownForm()
        {
            dForm = new DrillDownForm();
            dForm.Show();
        }
    }
}

VB.NET

Imports DevExpress.XtraPivotGrid
Imports System
Imports System.Collections.Generic

Namespace XtraPivotGrid_CreateDrillDownDataSourceAsync
    Partial Public Class Form1
        Inherits DevExpress.XtraEditors.XtraForm

        Private dForm As DrillDownForm
        Public Sub New()
            InitializeComponent()
            AddHandler Me.Load, AddressOf Form1_Load
            AddHandler pivotGridControl1.CellClick, AddressOf pivotGridControl1_CellClick
            ' This line of code is generated by Data Source Configuration Wizard
            linqServerModeSource1.QueryableSource = (New XtraPivotGrid_CreateDrillDownDataSourceAsync.DataClasses1DataContext()).Invoices
        End Sub
        Private Sub pivotGridControl1_CellClick(ByVal sender As Object, ByVal e As DevExpress.XtraPivotGrid.PivotCellEventArgs)
            Dim pivot As PivotGridControl = TryCast(sender, PivotGridControl)
            If dForm.IsDisposed Then
                LoadDrillDownForm()
            End If

            'Check whether an asynchronous operation is in progress.
            If Not pivot.IsAsyncInProgress Then

                ' Get the record set associated with the clicked cell.
                pivot.CreateDrillDownDataSourceAsync(e.ColumnIndex, e.RowIndex, 25, New List(Of String) From {"ProductName", "Quantity"}, Sub(result)
                    ' The 'result' parameter of the delegate returns an AsyncOperationResult instance.
                    ' The AsyncOperationResult.Value property contains a record set.
                    dForm.DataSource = CType(result.Value, PivotDrillDownDataSource)
                End Sub)
            End If
        End Sub
        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
            LoadDrillDownForm()
        End Sub
        Private Sub LoadDrillDownForm()
            dForm = New DrillDownForm()
            dForm.Show()
        End Sub
    End Class
End Namespace