Apply Application Model Changes to the Current View Immediately

• Jan 05, 2023
• 2 minutes to read

The example in this topic shows how to update the Application Model and apply the changes to a View immediately. Your application doesn’t reload the View if you follow the instructions below.

The code below implements two Actions that illustrate this approach to model customization.

C#

using System;
using DevExpress.ExpressApp;
using DevExpress.ExpressApp.Actions;
using DevExpress.ExpressApp.Scheduler.Win;
using DevExpress.ExpressApp.Win.Editors;
using DevExpress.Persistent.Base;
using DevExpress.Persistent.Base.General;
// ...
public class RefreshViewControlsAfterModelChangesViewController :
        ObjectViewController<ListView, IEvent> {
    public RefreshViewControlsAfterModelChangesViewController() {
        new SimpleAction(this, "SwitchMasterDetailMode", 
         PredefinedCategory.View.ToString(), (s, e) => {

            // Obtain and save the view
            ListView savedView = (ListView)Frame.View;

            // Detach the View from the Frame 
            // Don't dispose the old view
            if(Frame.SetView(view: null, true, null, disposeOldView: false)) {

                // Change the Application Model
                MasterDetailMode defaultMasterDetailMode = MasterDetailMode.ListViewOnly;
                savedView.Model.MasterDetailMode = 
                    savedView.Model.MasterDetailMode == defaultMasterDetailMode ?
                    MasterDetailMode.ListViewAndDetailView : defaultMasterDetailMode;

                // Load Model changes into the View 
                savedView.LoadModel(false);

                // Re-attach the View back to its Frame
                Frame.SetView(savedView);
            }
        });
        new SimpleAction(this, "SwitchEditor", 
         PredefinedCategory.View.ToString(), (s, e) => {
            // Same algorithm as above
            var savedView = View;
            if(Frame.SetView(view: null, true, null, disposeOldView: false)) {
                Type defaultListEditorType = Application.Model.Views.DefaultListEditor;
                savedView.Model.EditorType = 
                    savedView.Model.EditorType == defaultListEditorType ? 
                    typeof(SchedulerListEditor) : defaultListEditorType;
                savedView.LoadModel(false);
                Frame.SetView(savedView);
            }
        });
    }
}

VB.NET

Imports DevExpress.ExpressApp
Imports DevExpress.ExpressApp.Actions
Imports DevExpress.ExpressApp.Scheduler.Win
Imports DevExpress.ExpressApp.Win.Editors
Imports DevExpress.Persistent.Base
Imports DevExpress.Persistent.Base.General
' ...
Public Class RefreshViewControlsAfterModelChangesViewController
    Inherits ObjectViewController(Of ListView, IEvent)

    Public Sub New()
        New SimpleAction(Me, "SwitchMasterDetailMode",
         PredefinedCategory.View.ToString(), Sub(s, e)

            ' Obtain and save the view
            Dim savedView As ListView = CType(Frame.View, ListView)

            ' Detach the View from the Frame 
            ' Don't dispose the old view
            If Frame.SetView(view:=Nothing, True, Nothing, disposeOldView:=False) Then

                ' Change the Application Model
                Dim defaultMasterDetailMode As MasterDetailMode = MasterDetailMode.ListViewOnly
                savedView.Model.MasterDetailMode = If(savedView.Model.MasterDetailMode Is defaultMasterDetailMode, MasterDetailMode.ListViewAndDetailView, defaultMasterDetailMode)

                ' Load Model changes into the View
                savedView.LoadModel(False)

                ' Re-attach the View back to its Frame
                Frame.SetView(savedView)
            End If
        End Sub)
        New SimpleAction(Me, "SwitchEditor", PredefinedCategory.View.ToString(), Sub(s, e)
            ' Same algorithm as above
            Dim savedView = View
            If Frame.SetView(view:=Nothing, True, Nothing, disposeOldView:=False) Then
                Dim defaultListEditorType As Type = Application.Model.Views.DefaultListEditor
                savedView.Model.EditorType = If(savedView.Model.EditorType = defaultListEditorType, GetType(SchedulerListEditor), defaultListEditorType)
                savedView.LoadModel(False)
                Frame.SetView(savedView)
            End If
        End Sub)
    End Sub
End Class

Caution

We did not design this solution to be used in the Controller.Activated event handler or in an DevExpress.ExpressApp.Controller.OnActivated method override. In these cases, the solution usage may lead to unexpected results.