Devexpress xaf views

DevExpress XAF — Views

Views are the primary UI elements in XAF that display data. XAF auto-generates Views from the Application Model and business classes.

Prerequisites & Installation

Views are part of the core XAF framework — no additional module registration is required.

NuGet Packages (already included in XAF projects)

Package	Purpose
DevExpress.ExpressApp	ListView, DetailView, DashboardView, ShowViewParameters, CollectionSource, CollectionSourceDataAccessMode
DevExpress.Persistent.Base	[DefaultClassOptions], [NavigationItem], [VisibleInListView], [VisibleInDetailView]

Where to Place View-Related Code

Code Type	Location
Controllers that create/show views	MySolution.Module\Controllers\ (platform-agnostic)
Platform-specific UI customization	MySolution.Blazor.Server\Controllers\ or MySolution.Win\Controllers\
Non-persistent objects for custom views	MySolution.Module\BusinessObjects\

Using Statements

using DevExpress.ExpressApp;           // ListView, DetailView, DashboardView, ShowViewParameters
using DevExpress.Persistent.Base;      // DefaultClassOptionsAttribute, NavigationItemAttribute
using DevExpress.ExpressApp.SystemModule; // NavigationItemNodeGenerator, ShowNavigationItemController

Key Namespaces

Types	Namespace
ListView, DetailView, DashboardView, ShowViewParameters, TargetWindow, CollectionSourceDataAccessMode	DevExpress.ExpressApp
[DefaultClassOptions], [NavigationItem]	DevExpress.Persistent.Base
NavigationItemNodeGenerator	DevExpress.ExpressApp.SystemModule

ORM Detection

XPO vs EF Core affects default data access mode selection. Both ORMs support all 7 data access modes. When XPO is detected, the XPO-specific cast ((XPObjectSpace)objectSpace).Session is used inside views/controllers to access the underlying Session.

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View Type Hierarchy

View (abstract)
├── CompositeView (abstract, contains ViewItems)
│   ├── DashboardView       — displays multiple Views side-by-side
│   └── ObjectView (abstract)
│       ├── DetailView      — displays a single object
│       └── ListView        — displays a collection of objects

View Type	Purpose	Key Properties
ListView	Shows object collection in a grid/list	CollectionSource, Editor, ObjectTypeInfo, Model
DetailView	Shows a single object with property editors	CurrentObject, Items, ObjectSpace
DashboardView	Shows multiple Views side-by-side	Items (contains DashboardViewItems)

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Creating Views Programmatically

Refer to references/creating-views.md

When you need to:

• Create a ListView from type via Application.CreateListView(IObjectSpace, Type, bool) or with a CollectionSourceBase overload
• Create a DetailView with isRoot controlling Save/Cancel visibility and ObjectSpace lifecycle
• Create a DashboardView by ID via Application.CreateDashboardView
• Understand FindListViewId and CreateCollectionSource for custom list view setup
• Create non-persistent object views with NonPersistentObjectSpace
• Always create a dedicated ObjectSpace per new view — do not reuse this.ObjectSpace from the controller

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Showing Views

Refer to references/showing-views.md

When you need to:

• Show a view from an Action handler via ShowViewParameters (CreatedView, TargetWindow, Context, Controllers collection)
• Call Application.ShowViewStrategy.ShowView(svp, new ShowViewSource(Frame, null)) for programmatic display
• Create a PopupWindowShowAction with CustomizePopupWindowParams and selection handling
• Show a popup without an Action via Application.ShowViewStrategy.ShowViewInPopupWindow (modal popup shortcut)
• Replace the current view in the existing frame with Frame.SetView(view) — lower-level than ShowViewStrategy, used for programmatic in-frame navigation

TargetWindow Options

Value	Behavior
TargetWindow.Current	Replace the current View in the same Frame
TargetWindow.NewWindow	Open in a new tab/window
TargetWindow.NewModalWindow	Open as a modal popup
TargetWindow.Default	Platform-dependent default

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Navigation

Add to Navigation via Attributes

// Adds to "Default" navigation group, registers default List and Detail views, adds navigation item
[DefaultClassOptions]
public class Contact : BaseObject { }

// Adds to specific navigation group (group created automatically if it does not exist)
[NavigationItem("Management")]
public class Employee : BaseObject { }

Programmatic Navigation Item Addition

Add navigation items in code via ModelNodesGeneratorUpdater<NavigationItemNodeGenerator> (from DevExpress.ExpressApp.SystemModule), registered in ModuleBase.AddGeneratorUpdaters. See references/layout-and-dashboards.md for the full example.

View.IsRoot

Controls whether Save/Cancel Actions are shown:

• IsRoot = true — View creates its own dedicated ObjectSpace, shows Save/Cancel buttons, and manages its own persistence lifecycle
• IsRoot = false — View shares an ancestor view's ObjectSpace and its changes are committed when that root view saves

// Popup with its own Save button
DetailView view = Application.CreateDetailView(os, contact, isRoot: true);

// Embedded view that saves with parent
DetailView view = Application.CreateDetailView(os, contact, isRoot: false);

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Accessing View Data

Refer to references/view-data-access.md

When you need to:

• Access the current object via View.CurrentObject (null for empty List Views) or strongly typed ViewCurrentObject
• Subscribe to CurrentObjectChanged or SelectionChanged events
• Get selected objects from a ListView via SelectedObjects (IList) or e.SelectedObjects in Action handlers
• Apply named (keyed) filter criteria to ListView.CollectionSource.Criteria
• Sort via CollectionSource.Sorting and force reload with CollectionSource.ResetCollection()

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List View Data Access Modes

Set via IModelListView.DataAccessMode (CollectionSourceDataAccessMode enum, namespace DevExpress.ExpressApp) in code using a ModelNodesGeneratorUpdater. DefaultListViewOptionsAttribute does not have a DataAccessMode property.

Mode	Use Case	Loads
Client	Default for all regular List Views (EF Core and XPO), small datasets	All objects into memory
Queryable	Default for Blazor Tree List Views and Lookup List Views (both ORMs)	Displayed page only (deferred LINQ/query)
Server	Large datasets, synchronous server-side SQL	Displayed page only, editable
DataView	Complex objects, read-only	All, lightweight records
ServerView	Large + complex, synchronous	Displayed page, lightweight
InstantFeedback	Large datasets, async loading	Displayed page, async, separate session
InstantFeedbackView	Large + complex, async	Displayed page, async, lightweight

EF Core vs XPO: All 7 modes are available for both EF Core and XPO — no modes are exclusive to a single ORM. Default for all regular List Views is Client; Queryable is the default only for ASP.NET Core Blazor Tree List Views and Lookup List Views, regardless of ORM.

List View Modes & Editing

Refer to references/listview-modes.md

When you need to:

• Set data access mode via ModelNodesGeneratorUpdater (not via DefaultListViewOptionsAttribute)
• Enable in-place editing via [DefaultListViewOptions(true, NewItemRowPosition.None)] positional constructor or controller-side View.AllowEdit.SetItemValue("key", true) (AllowEdit is a BoolList, not a simple bool)
• Configure split layout (MasterDetailMode) to show ListView and DetailView side-by-side
• Set SplitLayout.Direction for horizontal/vertical orientation

Blazor InlineEditMode

Blazor-specific inline editing (distinct from WinForms AllowEdit):

Mode	Description
Inline	Edit row in place
Batch	Edit multiple rows, save all at once
EditForm	Edit in a form replacing the row
PopupEditForm	Edit in a popup form

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Detail View Layout & Dashboard Views

Refer to references/layout-and-dashboards.md

When you need to:

• Organize Detail View properties into groups and tabs with DetailViewLayoutAttribute
• Prevent layout auto-regeneration with FreezeLayout
• Create a DashboardView via ModelNodesGeneratorUpdater<ModelViewsNodesGenerator>
• Add navigation items for Dashboard Views

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Accessing View Items and UI Controls

Refer to references/view-items-controls.md

Important: FindItem, GetItems, and direct control access must be called in or after OnViewControlsCreated, not in OnActivated. Controls do not exist during OnActivated. The CustomizeViewItemControl<T> extension method (from DetailViewExtensions) defers internally, so it can be called in OnActivated.

When you need to:

• Get a specific property editor by name via View.FindItem("Name") as PropertyEditor (null-check the result) and subscribe to ValueChanged
• Get all editors of a type via View.GetItems<PropertyEditor>()
• Customize Blazor component models via View.CustomizeViewItemControl<T>(this, editor => { ... }) — lambda receives the typed view item; access editor.ComponentModel (Blazor) or editor.Control (WinForms)
• Access the underlying grid control in OnViewControlsCreated (Blazor DxGridListEditor, WinForms GridListEditor)
• Access nested ListView editors via ListPropertyEditor.ListView

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Non-Persistent Object Views

Show non-persistent objects (decorated with [DomainComponent]) in Views. Application.CreateObjectSpace(typeof(T)) returns a NonPersistentObjectSpace automatically for non-persistent types.

// Show a non-persistent object's Detail View in a popup
IObjectSpace os = Application.CreateObjectSpace(typeof(ReportParameters));
var parameters = os.CreateObject<ReportParameters>();
DetailView view = Application.CreateDetailView(os, parameters);
var svp = new ShowViewParameters(view);
svp.TargetWindow = TargetWindow.NewModalWindow;
svp.Context = TemplateContext.PopupWindow;
Application.ShowViewStrategy.ShowView(svp, new ShowViewSource(Frame, null));

For navigation-based non-persistent List Views, subscribe to ((NonPersistentObjectSpace)objectSpace).ObjectsGetting to populate e.Objects with data (e.g., from a REST API). Handle CommitChanges if write-back is needed.

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Troubleshooting

Symptom	Cause	Solution
View shows no data	ObjectSpace not created for the right type	Use Application.CreateObjectSpace(typeof(T))
Save/Cancel buttons missing	View.IsRoot = false	Pass isRoot: true to CreateDetailView
Controls / FindItem null in OnActivated	Controls do not exist yet in OnActivated	Use OnViewControlsCreated instead
Layout resets when class changes	FreezeLayout is false	Set IModelDetailView.FreezeLayout = true via generator updater or controller
Non-persistent properties blank in Server mode	Server mode limitation	Use PersistentAlias attribute
Split layout not showing	MasterDetailMode not set	Set MasterDetailMode = ListViewAndDetailView
Navigation item missing	Type not decorated	Add [DefaultClassOptions] or [NavigationItem("Group")], or use ModelNodesGeneratorUpdater<NavigationItemNodeGenerator>
Wrong data access mode	Mode set incorrectly	Use ModelNodesGeneratorUpdater to set IModelListView.DataAccessMode — not an attribute

Constraints & Rules

1. Code-only configuration: All view configuration via C# code (attributes, controllers, Application Model API). No XAFML files or visual designers.
2. Use OnViewControlsCreated to access underlying UI controls, not OnActivated.
3. Always create ObjectSpace before creating a View.
4. Version consistency: All DevExpress packages must use the same version.

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