XAF (eXpressApp Framework) — Skill Index

DevExpress XAF is a cross-platform .NET application framework for building business applications (Blazor Server and WinForms). It provides MVVM architecture, ORM integration (EF Core and XPO), security, validation, and rich module ecosystem.

Versions covered: v24.2 and v25.1 Platforms: Blazor Server, WinForms, Web API (OData) Official docs: https://docs.devexpress.com/eXpressAppFramework/112670/expressapp-framework DevExpress MCP: https://api.devexpress.com/mcp/docs

Sub-Skills — When to Use Each

Data Modeling

Skill	Load When
`xaf-xpo-models`	Defining XPO persistent objects (XPObject, BaseObject, associations, PersistentAlias)
`xaf-ef-models`	Defining EF Core entities (BaseObject EF, virtual properties, DbContext, migrations)
`xaf-nonpersistent`	Creating NonPersistent objects for custom data sources, API wrappers, input dialogs

UI Construction

Skill	Load When
`xaf-controllers`	Creating controllers, SimpleAction/PopupWindowShowAction/SingleChoiceAction/ParametrizedAction
`xaf-editors`	Working with built-in property editors, list editors, GridListEditor customization
`xaf-custom-editors`	Building custom property editors (Blazor/WinForms) or custom list editors
`xaf-conditional-appearance`	Conditionally hiding/disabling/coloring UI elements via [Appearance] attribute

Platform-Specific

Skill	Load When
`xaf-blazor-ui`	Blazor-specific UI, thread safety (InvokeAsync), Razor components in XAF, JS interop
`xaf-winforms-ui`	WinForms-specific UI, XtraGrid access, background workers, layout, splash

Security & Multi-Tenancy

Skill	Load When
`xaf-security`	Roles, permissions, authentication (Standard/AD/OAuth2), programmatic permission checks
`xaf-multi-tenant`	Multi-tenant SaaS apps with separate DB per tenant (v24.2+)

Services & API

Skill	Load When
`xaf-web-api`	Building/consuming XAF OData Web API (JWT, custom endpoints, $filter/$expand)
`xaf-validation`	Validation rules (RuleRequiredField, RuleCriteria, custom rules, programmatic validation)

Modules & Features

Skill	Load When
`xaf-reports`	XtraReports integration (setup, predefined reports, export, designer, parameters)
`xaf-dashboards`	Dashboard analytics (setup, data sources, designer, permissions)
`xaf-office`	File attachments, Spreadsheet editor, RichText editor, PDF viewer

Deployment

Skill	Load When
`xaf-deployment`	IIS/Azure/Docker for Blazor, ClickOnce/MSI for WinForms, migrations, license, logging

Diagnostics & Quality

Skill	Load When
`xaf-memory-leaks`	Diagnosing memory leaks, auditing event handler cleanup, reviewing ObjectSpace/CollectionSource lifetime

Quick Architecture Reference

MySolution/
├── MySolution.Module/          ← platform-agnostic (business objects, controllers, modules)
│   ├── BusinessObjects/
│   ├── Controllers/
│   └── MySolutionModule.cs
├── MySolution.Blazor.Server/   ← Blazor-specific (Program.cs, BlazorApplication.cs)
│   └── DatabaseUpdate/Updater.cs
├── MySolution.Win/             ← WinForms-specific (Program.cs, WinApplication.cs)
└── MySolution.WebApi/          ← Web API service (Program.cs, OData endpoints)

Key Concepts

ObjectSpace (IObjectSpace) — unit of work; wraps EF Core DbContext or XPO Session. Not thread-safe. Never store in singleton services.
XafApplication — application lifecycle, module registration, ObjectSpace creation.
ModuleBase — platform-agnostic module; registers business objects, controllers, navigation items.
Application Model — XML/in-memory model describing Views, Actions, Navigation — customizable without recompilation.
DatabaseUpdater — runs on startup to apply schema changes and seed data (Updater.cs).

Common Pitfalls (Quick Reference)

Pitfall	Fix
`ObjectSpace` in singleton service	Use `IObjectSpaceFactory` + `using var os = factory.CreateObjectSpace(...)`
`async/await` + `ConfigureAwait(false)` in Blazor	Remove `ConfigureAwait(false)` — Blazor needs sync context
Non-virtual EF Core properties	All EF Core entity properties must be `virtual`
XPO property without `SetPropertyValue`	Use backing field + `SetPropertyValue` for change tracking
`AddDbContext` instead of `AddDbContextFactory`	XAF requires `IDbContextFactory<T>`
NonPersistent provider registered first	Register `.AddNonPersistent()` after persistent providers

Useful Links

XAF Getting Started (Blazor): https://docs.devexpress.com/eXpressAppFramework/402189/getting-started/in-depth-tutorial-blazor
XAF Getting Started (WinForms): https://docs.devexpress.com/eXpressAppFramework/402684/getting-started/in-depth-tutorial-winforms-webforms
XAF API Reference: https://docs.devexpress.com/eXpressAppFramework/DevExpress.ExpressApp
DevExpress Examples (GitHub): https://github.com/DevExpress-Examples
DevExpress Support: https://supportcenter.devexpress.com
XAF Community (Blogs): https://community.devexpress.com/tags/XAF

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