DefaultReturnValueHandlerManager class final

Central orchestrator that coordinates multiple ReturnValueHandler implementations within JetLeaf’s MVC layer.

This composite pattern allows JetLeaf to delegate controller method return value handling dynamically, ensuring that the appropriate specialized handler is chosen for each scenario (e.g., view rendering, JSON serialization, redirects, etc.).

Overview

The DefaultReturnValueHandler maintains a registry of available ReturnValueHandlers. Each handler declares which return values it can process via canHandle.
When a controller method returns a value, the composite searches the ordered list of handlers and delegates execution to the first compatible one.

Handlers are automatically discovered and registered from the active ApplicationContext at startup, ensuring modular extensibility.

Responsibilities

Maintain an ordered list of return value handlers
Automatically discover and initialize handlers via ApplicationContext
Delegate return value processing to the first matching handler
Exclude advice-related controllers (@ControllerAdvice, @RestControllerAdvice)
Support concurrent-safe registration through internal synchronization

Example

final composite = DefaultReturnValueHandler();
composite.addHandlers([
  ViewRenderReturnValueHandler(),
  JsonReturnValueHandler(converters),
  StringReturnValueHandler(),
]);

final handler = composite.findHandler(method, returnValue, request);
if (handler != null) {
  await handler.handleReturnValue(returnValue, method, request, response, hm);
}

Handler Resolution Order

Handlers are ordered using AnnotationAwareOrderComparator, allowing priority control through the @Order annotation.

Lifecycle Integration

As an InitializingPod, this class automatically loads all available handler pods from the application context during startup. Handlers discovered at runtime can also be added manually via addHandler.

ReturnValueHandler — base strategy interface
JsonReturnValueHandler, StringReturnValueHandler, RedirectReturnValueHandler, VoidReturnValueHandler — concrete strategies
ApplicationContext — provides handler discovery and lifecycle management

Implemented types

ReturnValueHandlerManager

Annotations

@Author.new("Evaristus Adimonyemma")

Constructors

DefaultReturnValueHandlerManager(ContentNegotiationResolver _negotiationResolver): Central orchestrator that coordinates multiple ReturnValueHandler implementations within JetLeaf’s MVC layer.

Properties

hashCode → int: The hash code for this object.
no setterinherited
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited

Methods

addHandler(ReturnValueHandler handler) → void: Registers a new handler, replacing any existing instance of the same type.
addHandlers(Iterable<ReturnValueHandler> handlers) → void: Registers multiple handlers at once, clearing cached order.
canHandle(Method? method, Object? returnValue, ServerHttpRequest request) → bool: Determines whether this handler can handle the given return value.
override
equalizedProperties() → List<Object?>: Mixin-style contract for value-based equality, hashCode, and toString.
findHandler(Method? method, Object? returnValue, ServerHttpRequest request) → ReturnValueHandler?: Finds a ReturnValueHandler capable of processing the given returnValue.
override
getHandlers() → List<ReturnValueHandler>: Returns the ordered list of all registered ReturnValueHandlers managed by this instance.
override
getPackageName() → String: Represents an abstraction for identifying the package that an object, resource, or service belongs to.
getSupportedMediaTypes() → List<MediaType>: Returns the list of media types this handler supports by default.
override
handleReturnValue(Object? returnValue, Method? method, ServerHttpRequest request, ServerHttpResponse response, HandlerMethod? hm) → Future<void>: Processes the return value and writes the appropriate response.
override
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
onReady() → Future<void>: Interface to be implemented by pods that require initialization logic after their properties have been set by the container.
setApplicationContext(ApplicationContext applicationContext) → void: Sets the ApplicationContext that this component runs in.
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited