Bind to XPO Data Sources

• Jan 30, 2022
• 6 minutes to read

Instant Feedback

In this example, the GridControl is bound to an XPInstantFeedbackSource object. This object activates an Instant Feedback UI Mode. In this mode, you will no longer experience any UI freezing. Data operations are performed asynchronously in a background thread. The GridControl and your application are always highly responsive.

View Example

MainWindow.xaml

<Window x:Class="InstantFeedbackMode.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid"
        xmlns:dx="http://schemas.devexpress.com/winfx/2008/xaml/core">
    <Grid>
        <dxg:GridControl Name="grid" AutoGenerateColumns="AddNew" />
    </Grid>
</Window>

MainWindow.xaml.cs

using System;
using System.Windows;
using DevExpress.Data.Filtering;
using DevExpress.Xpf.Grid;
using DevExpress.Xpo;
using DevExpress.Xpf.Core;

namespace InstantFeedbackMode {
    public partial class MainWindow : Window {

        public MainWindow() {
            InitDAL();
            // Generates test data - 100,000 records.
            GenerateTestData(100000);
            InitializeComponent();

            // Creates and initializes the data source which activates the Instant Feedback UI Mode.
            XPInstantFeedbackSource instantDS = new XPInstantFeedbackSource(typeof(TestObject));
            instantDS.ResolveSession += new EventHandler<ResolveSessionEventArgs>(instantDS_ResolveSession);
            instantDS.DismissSession += new EventHandler<ResolveSessionEventArgs>(instantDS_DismissSession);

            // Bind the grid.
            grid.ItemsSource = instantDS;
        }

        void instantDS_ResolveSession(object sender, ResolveSessionEventArgs e) {
            e.Session = new UnitOfWork();
        }

        void instantDS_DismissSession(object sender, ResolveSessionEventArgs e) {
            IDisposable session = e.Session as IDisposable;
            if (session != null) {
                session.Dispose();
            }
        }

        private static void InitDAL() {
            XpoDefault.Session = null;
            XpoDefault.DataLayer = XpoDefault.GetDataLayer(
                DevExpress.Xpo.DB.AccessConnectionProvider.GetConnectionString("test.mdb"),
                DevExpress.Xpo.DB.AutoCreateOption.DatabaseAndSchema
                );
        }

        private void GenerateTestData(int recordCount) {
            using (UnitOfWork s = new UnitOfWork()) {
                if (s.FindObject<TestObject>(null) != null) return;
                for (int i = 0; i < recordCount; i++) {
                    TestObject o = new TestObject(s) { HasAttachment = false, Sent = DateTime.Now, Subject = string.Format("Subject {0}", i) };
                }
                s.CommitChanges();
            }
        }
    }
}

MainWindow.xaml.vb

Imports System
Imports System.Windows
Imports DevExpress.Data.Filtering
Imports DevExpress.Xpf.Grid
Imports DevExpress.Xpo
Imports DevExpress.Xpf.Core

Namespace InstantFeedbackMode
    Partial Public Class MainWindow
        Inherits Window

        Public Sub New()
            InitDAL()
            ' Generates test data - 100,000 records.
            GenerateTestData(100000)
            InitializeComponent()

            ' Creates and initializes the data source which activates the Instant Feedback UI Mode.
            Dim instantDS As New XPInstantFeedbackSource(GetType(TestObject))
            AddHandler instantDS.ResolveSession, AddressOf instantDS_ResolveSession
            AddHandler instantDS.DismissSession, AddressOf instantDS_DismissSession

            ' Bind the grid.
            grid.ItemsSource = instantDS
        End Sub

        Private Sub instantDS_ResolveSession(ByVal sender As Object, ByVal e As ResolveSessionEventArgs)
            e.Session = New UnitOfWork()
        End Sub

        Private Sub instantDS_DismissSession(ByVal sender As Object, ByVal e As ResolveSessionEventArgs)
            Dim session As IDisposable = TryCast(e.Session, IDisposable)
            If session IsNot Nothing Then
                session.Dispose()
            End If
        End Sub

        Private Shared Sub InitDAL()
            XpoDefault.Session = Nothing
            XpoDefault.DataLayer = XpoDefault.GetDataLayer(DevExpress.Xpo.DB.AccessConnectionProvider.GetConnectionString("test.mdb"), DevExpress.Xpo.DB.AutoCreateOption.DatabaseAndSchema)
        End Sub

        Private Sub GenerateTestData(ByVal recordCount As Integer)
            Using s As New UnitOfWork()
                If s.FindObject(Of TestObject)(Nothing) IsNot Nothing Then
                    Return
                End If
                For i As Integer = 0 To recordCount - 1
                    Dim o As New TestObject(s) With {.HasAttachment = False, .Sent = Date.Now, .Subject = String.Format("Subject {0}", i)}
                Next i
                s.CommitChanges()
            End Using
        End Sub
    End Class
End Namespace

DataModel.cs

using System;
using DevExpress.Xpo;

namespace InstantFeedbackMode {
    public class TestObject : XPObject {
        string _subject;
        public string Subject {
            get { return _subject; }
            set { SetPropertyValue<string>("Subject", ref _subject, value); }
        }
        DateTime _sent;
        public DateTime Sent {
            get { return _sent; }
            set { SetPropertyValue<DateTime>("Sent", ref _sent, value); }
        }

        bool _hasAttachment;
        public bool HasAttachment {
            get { return _hasAttachment; }
            set { SetPropertyValue<bool>("HasAttachment", ref _hasAttachment, value); }
        }
        public TestObject(Session session) : base(session) { }
        public TestObject() : base(Session.DefaultSession) { }
        public override void AfterConstruction() { base.AfterConstruction(); }
    }
}

DataModel.vb

Imports System
Imports DevExpress.Xpo

Namespace InstantFeedbackMode
    Public Class TestObject
        Inherits XPObject

        Private _subject As String
        Public Property Subject() As String
            Get
                Return _subject
            End Get
            Set(ByVal value As String)
                SetPropertyValue(Of String)("Subject", _subject, value)
            End Set
        End Property
        Private _sent As Date
        Public Property Sent() As Date
            Get
                Return _sent
            End Get
            Set(ByVal value As Date)
                SetPropertyValue(Of Date)("Sent", _sent, value)
            End Set
        End Property

        Private _hasAttachment As Boolean
        Public Property HasAttachment() As Boolean
            Get
                Return _hasAttachment
            End Get
            Set(ByVal value As Boolean)
                SetPropertyValue(Of Boolean)("HasAttachment", _hasAttachment, value)
            End Set
        End Property
        Public Sub New(ByVal session As Session)
            MyBase.New(session)
        End Sub
        Public Sub New()
            MyBase.New(Session.DefaultSession)
        End Sub
        Public Overrides Sub AfterConstruction()
            MyBase.AfterConstruction()
        End Sub
    End Class
End Namespace

Server Mode

This example shows how to provide the GridControl with data using the eXpress Persistent Objects (XPO).

1. Create a new persistent class representing a data object TestObject:

   C#

   using System;
   using DevExpress.Xpo;
   
   namespace XpoServMode {
       public class TestObject : XPObject {
           string _subject;
           public string Subject {
               get { return _subject; }
               set { SetPropertyValue<string>("Subject", ref _subject, value); }
           }
           DateTime _sent;
           public DateTime Sent {
               get { return _sent; }
               set { SetPropertyValue<DateTime>("Sent", ref _sent, value); }
           }
   
           bool _hasAttachment;
           public bool HasAttachment {
               get { return _hasAttachment; }
               set { SetPropertyValue<bool>("HasAttachment", ref _hasAttachment, value); }
           }
           public TestObject(Session session) : base(session) { }
           public TestObject() : base(Session.DefaultSession) { }
           public override void AfterConstruction() { base.AfterConstruction(); }
       }
   }
   

   VB.NET

   Imports System
   Imports DevExpress.Xpo
   
   Namespace XpoServMode
       Public Class TestObject
           Inherits XPObject
   
           Private _subject As String
   
           Public Property Subject As String
               Get
                   Return _subject
               End Get
               Set(ByVal value As String)
                   SetPropertyValue(Of String)("Subject", _subject, value)
               End Set
           End Property
   
           Private _sent As DateTime
   
           Public Property Sent As DateTime
               Get
                   Return _sent
               End Get
               Set(ByVal value As DateTime)
                   SetPropertyValue(Of DateTime)("Sent", _sent, value)
               End Set
           End Property
   
           Private _hasAttachment As Boolean
   
           Public Property HasAttachment As Boolean
               Get
                   Return _hasAttachment
               End Get
               Set(ByVal value As Boolean)
                   SetPropertyValue(Of Boolean)("HasAttachment", _hasAttachment, value)
               End Set
           End Property
   
           Public Sub New(ByVal session As Session)
               MyBase.New(session)
           End Sub
   
           Public Sub New()
               MyBase.New(Session.DefaultSession)
           End Sub
   
           Public Overrides Sub AfterConstruction()
               MyBase.AfterConstruction()
           End Sub
       End Class
   End Namespace
   

2. Define a database to store data.

3. Bind the GridControl to a new XPCollection object:

   XAML

   <Window
           xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
           xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
           xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
           xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
           xmlns:local="clr-namespace:XpoServMode"
           xmlns:dxg="http://schemas.devexpress.com/winfx/2008/xaml/grid" x:Class="XpoServMode.MainWindow"
           mc:Ignorable="d"
           Title="MainWindow" Height="450" Width="800">
           <dxg:GridControl Name="grid" AutoGenerateColumns="AddNew" EnableSmartColumnsGeneration="True">
               <dxg:GridControl.TotalSummary>
                   <dxg:GridSummaryItem Alignment="Left" FieldName="Oid" SummaryType="Count"/>
               </dxg:GridControl.TotalSummary>
               <dxg:GridControl.View>
                   <dxg:TableView ShowFixedTotalSummary="True"/>
               </dxg:GridControl.View>
           </dxg:GridControl>
   </Window>
   

   C#

   using DevExpress.Xpo;
   using System;
   using System.Windows;
   
   namespace XpoServMode {
       public partial class MainWindow : Window {
           public MainWindow() {
               InitDAL();
               GenerateTestData(100000);
               InitializeComponent();
   
               var session = new UnitOfWork(XpoDefault.DataLayer);
               var serverDS = new XPServerCollectionSource(session, typeof(TestObject));
               grid.ItemsSource = serverDS;
           }
   
           private static void InitDAL() {
               XpoDefault.Session = null;
               XpoDefault.DataLayer = XpoDefault.GetDataLayer(
                   DevExpress.Xpo.DB.AccessConnectionProvider.GetConnectionString("test.mdb"),
                   DevExpress.Xpo.DB.AutoCreateOption.DatabaseAndSchema
                   );
           }
           void GenerateTestData(int recordCount) {
               using (UnitOfWork s = new UnitOfWork()) {
                   if (s.FindObject<TestObject>(null) != null) return;
                   for (int i = 0; i < recordCount; i++) {
                       TestObject o = new TestObject(s) { HasAttachment = false, Sent = DateTime.Now, Subject = string.Format("Subject {0}", i) };
                   }
                   s.CommitChanges();
               }
           }
       }
   }
   

   VB.NET

   Imports DevExpress.Xpo
   Imports System
   Imports System.Windows
   
   Namespace XpoServMode
       Public Partial Class MainWindow
           Inherits Window
   
           Public Sub New()
               InitDAL()
               GenerateTestData(100000)
               InitializeComponent()
               Dim session = New UnitOfWork(XpoDefault.DataLayer)
               Dim serverDS = New XPServerCollectionSource(session, GetType(TestObject))
               grid.ItemsSource = serverDS
           End Sub
   
           Private Shared Sub InitDAL()
               XpoDefault.Session = Nothing
               XpoDefault.DataLayer = XpoDefault.GetDataLayer(DevExpress.Xpo.DB.AccessConnectionProvider.GetConnectionString("test.mdb"), DevExpress.Xpo.DB.AutoCreateOption.DatabaseAndSchema)
           End Sub
   
           Private Sub GenerateTestData(ByVal recordCount As Integer)
               Using s As UnitOfWork = New UnitOfWork()
                   If s.FindObject(Of TestObject)(Nothing) IsNot Nothing Then Return
   
                   For i As Integer = 0 To recordCount - 1
                       Dim o As TestObject = New TestObject(s) With {
                           .HasAttachment = False,
                           .Sent = DateTime.Now,
                           .Subject = String.Format("Subject {0}", i)
                       }
                   Next
   
                   s.CommitChanges()
               End Using
           End Sub
       End Class
   End Namespace
   

The following examples demonstrate how to use these data sources to bind data to a WPF data grid:

• How to Implement the Instant Feedback Mode (XPO)
• How to Create a CRUD Application with XPO and WPF
• How to Bind Data to WPF Controls Using XPServerModeView or XPInstantFeedbackView
• How to Use DXGrid in Server Mode with XPO