vaadin/flow 25.1.0

Vaadin Flow 25.1.0

on GitHub

Vaadin Flow 25.1 introduces production-ready reactive UI state management aka Signals API, along with the free browser-less testing framework (aka old commercial UI unit testing) and various other enhancements and bug-fixes.

Breaking Changes

Signal API Changes

• Enforce signal reads in computed signals and effects
  Commit · Pull request

  Signals now enforce reactive context requirements when reading values in computed signals and effects.

• Standardize signal callback interfaces
  Commit · Pull request

• Move component-bound effect to Signal public API
  Commit · Pull request

• Remove WritableSignal interface and simplify signal API
  Commit · Pull request

  Simplified the signal API by removing the WritableSignal interface and consolidating functionality.

• Rename Signal value()/value(T) to get()/set(T)
  Commit · Pull request

  Renamed signal methods for clarity and consistency with Java conventions.

• Restructure signals package for clarity between shared and local signals
  Commit · Pull request

• Merge signals module into flow-server
  Commit · Pull request

  The separate signals module has been merged into flow-server for better integration.

• Rename Binder.Binding.value() to valueSignal() and return signal
  Commit · Pull request

  Reworks Binding.value() to return a ValueSignal instead of the raw value.

• Rename getValidationStatus() to validationStatusSignal()
  Commit · Pull request

  Renames the Binder method to better reflect that it returns a Signal.

• Make localeSignal() read-only on VaadinSession and UI
  Pull request

  The locale signal is now read-only to prevent accidental modifications. Use setLocale() to change the locale.

• Split computed into separate cached and direct versions
  Pull request

  Signal.computed() now creates a cached computed signal by default. For non-cached behavior, use Signal.computedDirect().

Component and API Changes

• Make wrapperElement field private
  Commit · Pull request

  The wrapperElement field is now private and moved to UIInternals.

• Prevent lumo utility classes from being imported automatically
  Commit · Pull request · Issue

• Set proper value of isFromClient when using Focusable focus() and blur()
  Commit · Pull request

  The isFromClient flag now properly reflects the origin of focus/blur events.

• BeforeEvent target as extends Component
  Commit · Pull request

Browser Compatibility

• Update old browser check to verify compatibility with Vaadin 25+
  Commit · Pull request · Issue

  Updated browser compatibility check to ensure Popover API availability, required for Vaadin 25 web components.

New Features

Signal-Based Reactive Programming

• Use type-parameter-level nullability for Signal APIs
  Commit · Pull request

• Add custom equality checker support to ValueSignal
  Commit · Pull request

• Throw IllegalStateException when Signal.get() is called outside a reactive context
  Commit · Pull request

• Make shared signals use asynchronous signal trees
  Commit · Pull request

• Detect accidental sharing of ValueSignal with background threads
  Commit · Pull request

• Detect accidental sharing of local signals between sessions
  Commit · Pull request

• Automatic repeatable reads for shared signals while session is locked
  Commit · Pull request

• Make shared signals Serializable
  Commit · Pull request

• Add local ListSignal for per-entry reactive lists
  Commit · Pull request

• Add two-way computed signals via WritableSignal.map
  Commit · Pull request

• Remove FLOW_FULLSTACK_SIGNALS feature flag and enable signals by default
  Commit · Pull request

• Prevent serialization of shared signals
  Commit · Pull request

• Add equality checker to ListSignal
  Commit · Pull request

• Add moveTo method to ListSignal
  Commit · Pull request

• Add SignalBinding with rich BindingContext for bind methods
  Pull request

  Provides more context and control over signal bindings.

• Allow setProperty if signal write callback is present
  Pull request

  Enables two-way bindings with custom write logic.

• Add helpers to get all items from a list signal
  Pull request

  Convenience methods for working with list signal contents.

Component Signal Bindings

• Add signal bind methods for NativeDetails, HtmlObject, and HasStyle
  Commit · Pull request

• Add bindRequiredIndicatorVisible to HasValue / HasValueAndElement
  Commit · Pull request

• Add windowSizeSignal() to Page for reactive window size tracking
  Commit · Pull request

• Add localeSignal() to UI and VaadinSession
  Commit

• Add signal binding constructors and methods for HTML components
  Commit · Pull request

• Add bindChildren method to HasComponents mix-in
  Commit · Pull request

• Add Anchor signal-based constructors
  Commit · Pull request

• Add FieldSet::bindLegendText
  Commit · Pull request

• Add Html(signal) and bindHtmlContent(signal)
  Commit · Pull request

• Add bindWidth(Signal) and bindHeight(Signal)
  Commit · Pull request

• Add bindReadOnly(Signal)
  Commit · Pull request

• Add HasValidation::bindErrorMessage and bindInvalid
  Commit · Pull request

• Add HasPlaceholder::bindPlaceholder(Signal)
  Commit · Pull request

• Add HasHelper::bindHelperText
  Commit · Pull request

• Add HasTheme::bindThemeName(String, Signal)
  Commit · Pull request

• Add signal constructor to HTML components
  Commit · Pull request · Issue

• Add HasValue::bindValue(WritableSignal)
  Commit · Pull request · Issue

• Add HasText::bindText
  Commit · Pull request · Issue

• Add Component::bindVisible
  Commit · Pull request · Issue

• Add HasEnabled::bindEnabled
  Commit · Pull request · Issue

• Add HasDataView::bindItems for reactive list binding
  Commit · Pull request

• Add bindItems to HasDataProvider components
  Pull request

  Reactive data binding for data provider components.

• Throw binding exception if setItems is called while an active signal binding
  Pull request

  Prevents conflicting data sources by throwing an exception.

• Add setTestId/getTestId convenience methods to Component
  Pull request

  Simplifies setting and retrieving test identifiers for components.

Data Binding and Validation

• Enhance Binder with cross-field validation
  Commit · Pull request

• Make bindProperty support write callbacks
  Commit · Pull request

• Make two-way signal bindings explicit with a write callback parameter
  Commit · Pull request

• Add callback helper methods for bindValue
  Commit · Pull request

Data Components

• Add protected API to regenerate data in viewport
  Commit · Pull request

  Added protected refreshViewport method to DataCommunicator and HierarchicalDataCommunicator.

• Implement getItems(offset, limit) in DataView
  Commit · Pull request · Issue

  Added efficient query-based item retrieval with offset/limit support.

• Add Element.flashClass() for CSS animation-based visual feedback
  Commit · Pull request

  Add a flashClass(String) method to Element that temporarily applies a CSS class to trigger an animation, then auto-removes it when the animation ends.

Browserless Testing

• Add browserless mode flag to suppress dev server warnings in browerless tests
  Commit · Pull request

File Uploads

• Add upload rejection API with optional messages
  Commit · Pull request

Spring Integration

• Improve SpringInstantiator
  Commit · Pull request · Issue

  Better handling of multiple beans using Spring's resolution logic (Primary, Fallback, etc.).

Build and Development

• BuildFrontend incremental build
  Pull request

  Frontend builds now support incremental compilation for faster development cycles.

• Retain local signal values during hotswap
  Pull request

  Signal state is preserved during hot reload, improving development experience.

• Content-hash cache busting for Stylesheet URLs
  Pull request

  Stylesheet URLs now include content hashes to ensure cache invalidation when files change.

• Preserve scroll position of all scrollable elements after hot-swap
  Pull request

  Scroll positions are maintained across hot reloads for better developer experience.

• Add git pre-commit hook for automatic code formatting
  Commit · Pull request

• Disable client statistics
  Commit · Pull request

• Delegate no-routes handling to Copilot
  Commit · Pull request

• Auto-load Aura theme CSS when no AppShellConfigurator exists
  Commit · Pull request

• Add local web components plugin to vite.generated.ts
  Pull request

  Better support for local web component development.

• Apply ElementEffect once when created
  Pull request

  Optimizes effect execution during initialization.

• Skip ElementEffect callback on reattach when no signals changed
  Pull request

  Improves performance by avoiding unnecessary effect re-execution.

Component API Improvements

• Move HasOrderedComponents methods to HasComponents
  Pull request

  HasOrderedComponents is now deprecated; use HasComponents instead.

Other Features

• Add allowInert attribute to DomEvent annotation
  Commit · Pull request

• Add customizable sync error messages for session desync scenarios
  Commit · Pull request

• Move to com.interaso.webpush
  Commit · Pull request

Testing Improvements

This release includes extensive migration to JUnit 5 (Jupiter) across the codebase, improving test maintainability and leveraging modern testing features. Multiple test modules have been migrated including flow-data, flow-dnd, flow-lit-template, flow-polymer-template, flow-polymer2lit, flow-build-tools, flow-plugins, and vaadin-dev-server.

Dependency Updates

• ⚠️ Spring Boot updated to 4.0.4, this patch version is important to use because of Jackson compatibility.
• Node.js updated to 24.14.1
• Jackson updated to 3.1.0
• TestBench updated to 10.1.0
• JAXB updated to 4.0.7
• Byte Buddy updated to 1.18.5
• NullAway updated to 0.13.1
• JUnit Jupiter updated to 6.0.3
• Spotless Maven Plugin updated to latest version
• Frontend dependencies updated to latest versions

Thanks For Contributions!

@knoobie @patrick-audit @AB-xdev @OriginalFelix @sgpublic @lycoris106

For more details, see the full comparison on GitHub.

Changes since 25.1.0-beta1