Package org.axonframework.modelling.entity.annotation

Class AnnotatedEntityMetamodel<E>

java.lang.Object

org.axonframework.modelling.entity.annotation.AnnotatedEntityMetamodel<E>

Type Parameters:

E - The type of entity this metamodel describes.

All Implemented Interfaces:

DescribableComponent, EntityMetamodel<E>, EntityEvolver<E>

@Internal
public class AnnotatedEntityMetamodel<E>
extends Object
implements EntityMetamodel<E>, DescribableComponent

An EntityMetamodel implementation that uses reflection to inspect the entity. It will detect annotated command- and event-handling methods, as well as child entities annotated with EntityMember. Everything that is discovered is then registered to a delegate EntityMetamodel, so that essentially a declared metamodel is built of which it's structure is clearly defined.

Besides normal EntityMetamodel operations, this metamodel also provides a means to get the expected representation of a command or event handler based on the QualifiedName of the message type. This is useful for determining the payload type of a command or event handler when multiple handlers are present for the same message type.

NOTE: This class is a complete rewrite of the pre-5.0.0 org.axonframework.modelling.command.inspection.AnnotatedAggregateMetaModelFactory. Both scan the class for annotated methods and fields, but the AnnotatedEntityModel dropped aggregate versioning (conflict resolution), no longer required an id in the entity, and creates a declarative metamodel instead of relying on reflection at runtime.

This class is marked Internal because it is an annotation-scanning implementation detail: it is built by the framework from the entity class and exposes reflection-specific behavior (such as getExpectedRepresentation(QualifiedName)) that is not part of the EntityMetamodel contract. Users should interact with entities through the EntityMetamodel interface, which can be freely decorated or replaced, rather than depending on this concrete type.

Since:

3.1.0

Author:

Mitchell Herrijgers, Allard Buijze

Field Summary

Fields inherited from interface org.axonframework.modelling.entity.EntityMetamodel

CREATE_WITHOUT_LOAD

Method Summary

Modifier and Type	Method	Description
void	describeTo(ComponentDescriptor descriptor)	Describe the properties of this DescribableComponent with the given descriptor.
Class<E>	entityType()	Returns the Class of the entity this metamodel describes.
E	evolve(E entity, EventMessage event, ProcessingContext context)	Evolve the given entity by applying the given event to it.
static <E> AnnotatedEntityMetamodel<E>	forConcreteType(Class<E> entityType, ParameterResolverFactory parameterResolverFactory, MessageTypeResolver messageTypeResolver, MessageConverter messageConverter, EventConverter eventConverter)	Instantiate an annotated EntityMetamodel of a concrete entity type.
static <E> AnnotatedEntityMetamodel<E>	forPolymorphicSealedType(Class<E> entityType, ParameterResolverFactory parameterResolverFactory, MessageTypeResolver messageTypeResolver, MessageConverter messageConverter, EventConverter eventConverter)	Instantiate an annotated EntityMetamodel of a polymorphic sealed entity type.
static <E> AnnotatedEntityMetamodel<E>	forPolymorphicType(Class<E> entityType, Set<Class<? extends E>> concreteTypes, ParameterResolverFactory parameterResolverFactory, MessageTypeResolver messageTypeResolver, MessageConverter messageConverter, EventConverter eventConverter)	Instantiate an annotated EntityMetamodel of a polymorphic entity type.
@Nullable Class<?>	getExpectedRepresentation(QualifiedName qualifiedName)	Returns the Class of the expected representation for handlers of the given qualifiedName.
MessageStream.Single<CommandResultMessage>	handleCreate(CommandMessage message, ProcessingContext context)	Handles the given CommandMessage as the creation of a new entity.
MessageStream.Single<CommandResultMessage>	handleInstance(CommandMessage message, E entity, ProcessingContext context)	Handles the given CommandMessage for the given entity.
Set<QualifiedName>	supportedCommands()	Returns the set of all QualifiedNames that this metamodel supports for command handlers, both creational and instance commands.
Set<QualifiedName>	supportedCreationalCommands()	Returns the set of all QualifiedNames that this metamodel supports for creating entities.
Set<QualifiedName>	supportedInstanceCommands()	Returns the set of all QualifiedNames that this metamodel supports for instance commands.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

forConcreteType

public static <E> AnnotatedEntityMetamodel<E> forConcreteType(Class<E> entityType,
 ParameterResolverFactory parameterResolverFactory,
 MessageTypeResolver messageTypeResolver,
 MessageConverter messageConverter,
 EventConverter eventConverter)

Instantiate an annotated EntityMetamodel of a concrete entity type.

Type Parameters:

E - The type of entity this metamodel describes.

Parameters:

entityType - The concrete entity type this metamodel describes.

parameterResolverFactory - The ParameterResolverFactory to use for resolving parameters.

messageTypeResolver - The MessageTypeResolver to use for resolving message types from payload classes.

messageConverter - The converter used to convert the Message.payload() to the desired format.

eventConverter - The converter used to convert the Message.payload() to the desired format.

Returns:

An annotated EntityMetamodel backed by a ConcreteEntityMetamodel for the given entity type.

forPolymorphicSealedType

public static <E> AnnotatedEntityMetamodel<E> forPolymorphicSealedType(Class<E> entityType,
 ParameterResolverFactory parameterResolverFactory,
 MessageTypeResolver messageTypeResolver,
 MessageConverter messageConverter,
 EventConverter eventConverter)

Instantiate an annotated EntityMetamodel of a polymorphic sealed entity type. At least one concrete type must exist, as this metamodel is meant to describe a polymorphic entity type with multiple concrete implementations.

Type Parameters:

E - The type of the polymorphic entity.

Parameters:

entityType - The polymorphic sealed entity type this metamodel describes.

parameterResolverFactory - The ParameterResolverFactory to use for resolving parameters.

messageTypeResolver - The MessageTypeResolver to use for resolving message types from payload classes.

messageConverter - The converter used to convert the Message.payload() to the desired format.

eventConverter - The event converter used to convert the Message.payload() to the desired format.

Returns:

An annotated EntityMetamodel backed by a PolymorphicEntityMetamodel for the given entity type.

See Also:

• forPolymorphicType(Class, Set, ParameterResolverFactory, MessageTypeResolver, MessageConverter, EventConverter)

forPolymorphicType

public static <E> AnnotatedEntityMetamodel<E> forPolymorphicType(Class<E> entityType,
 Set<Class<? extends E>> concreteTypes,
 ParameterResolverFactory parameterResolverFactory,
 MessageTypeResolver messageTypeResolver,
 MessageConverter messageConverter,
 EventConverter eventConverter)

Instantiate an annotated EntityMetamodel of a polymorphic entity type. At least one concrete type must be supplied, as this metamodel is meant to describe a polymorphic entity type with multiple concrete implementations.

Type Parameters:

E - The type of the polymorphic entity.

Parameters:

entityType - The polymorphic entity type this metamodel describes.

concreteTypes - The concrete types of the polymorphic entity type.

parameterResolverFactory - The ParameterResolverFactory to use for resolving parameters.

messageTypeResolver - The MessageTypeResolver to use for resolving message types from payload classes.

messageConverter - The converter used to convert the Message.payload() to the desired format.

eventConverter - The event converter used to convert the Message.payload() to the desired format.

Returns:

An annotated EntityMetamodel backed by a PolymorphicEntityMetamodel for the given entity type.

getExpectedRepresentation

public @Nullable Class<?> getExpectedRepresentation(QualifiedName qualifiedName)

Returns the Class of the expected representation for handlers of the given qualifiedName.

Parameters:

qualifiedName - The QualifiedName of the handler to look for.

Returns:

The Class of the expected representation for handlers of the given qualifiedName, or null if no such representation is found.

supportedCommands

public Set<QualifiedName> supportedCommands()

Description copied from interface: EntityMetamodel

Returns the set of all QualifiedNames that this metamodel supports for command handlers, both creational and instance commands. This is the union of the EntityMetamodel.supportedCreationalCommands() and EntityMetamodel.supportedInstanceCommands() methods.

Specified by:

supportedCommands in interface EntityMetamodel<E>

Returns:

A set of QualifiedName instances representing the supported command names.

supportedCreationalCommands

public Set<QualifiedName> supportedCreationalCommands()

Description copied from interface: EntityMetamodel

Returns the set of all QualifiedNames that this metamodel supports for creating entities. These are the command types that can be used to create an entity of this type through the EntityMetamodel.handleCreate(org.axonframework.messaging.commandhandling.CommandMessage, org.axonframework.messaging.core.unitofwork.ProcessingContext) method.

Specified by:

supportedCreationalCommands in interface EntityMetamodel<E>

Returns:

A set of QualifiedName instances representing the supported command names.

supportedInstanceCommands

public Set<QualifiedName> supportedInstanceCommands()

Description copied from interface: EntityMetamodel

Returns the set of all QualifiedNames that this metamodel supports for instance commands. These are the command types that can be used on entity instances of this type through the EntityMetamodel.handleInstance(org.axonframework.messaging.commandhandling.CommandMessage, E, org.axonframework.messaging.core.unitofwork.ProcessingContext) method.

Specified by:

supportedInstanceCommands in interface EntityMetamodel<E>

Returns:

A set of QualifiedName instances representing the supported command names.

handleCreate

public MessageStream.Single<CommandResultMessage> handleCreate(CommandMessage message,
 ProcessingContext context)

Description copied from interface: EntityMetamodel

Handles the given CommandMessage as the creation of a new entity. It is up to the registered command handler to create the entity.

This method is used to handle commands for new entities. If you want to handle commands for existing entities, use the EntityMetamodel.handleInstance(org.axonframework.messaging.commandhandling.CommandMessage, E, org.axonframework.messaging.core.unitofwork.ProcessingContext) method instead. If the command handler is only known as an instance command handler and this method is called, it will result in a failed message stream.

Specified by:

handleCreate in interface EntityMetamodel<E>

Parameters:

message - The CommandMessage to handle.

context - The ProcessingContext for the command.

Returns:

A stream with a message containing the result of the command handling, which may be a CommandResultMessage or an error message.

handleInstance

public MessageStream.Single<CommandResultMessage> handleInstance(CommandMessage message,
 E entity,
 ProcessingContext context)

Description copied from interface: EntityMetamodel

Handles the given CommandMessage for the given entity. If any of its children can handle the command, it will be delegated to them. Otherwise, the command will be handled by this metamodel. If the command is not handled by this metamodel or any of its children, an MessageStream.failed(Throwable) will be returned.

This method is used to handle commands for existing entities. If you want to handle commands for new entities, use the EntityMetamodel.handleCreate(org.axonframework.messaging.commandhandling.CommandMessage, org.axonframework.messaging.core.unitofwork.ProcessingContext) method instead. If the command handler is only known as a creational command handler and this method is called, it will result in a failed message stream.

Specified by:

handleInstance in interface EntityMetamodel<E>

Parameters:

message - The CommandMessage to handle.

entity - The entity instance to handle the command for.

context - The ProcessingContext for the command.

Returns:

A stream with a message containing the result of the command handling, which may be a CommandResultMessage or an error message.

describeTo

public void describeTo(ComponentDescriptor descriptor)

Description copied from interface: DescribableComponent

Describe the properties of this DescribableComponent with the given descriptor.

Components should call the appropriate describeProperty methods on the descriptor to register their properties. The descriptor is responsible for determining how these properties are formatted and structured in the final output.

Best Practices: As a general rule, all relevant fields of a DescribableComponent implementation should be described in this method. However, developers have discretion to include only the fields that make sense in the context. Not every field may be meaningful for description purposes, especially internal implementation details. Furthermore, components might want to expose different information based on their current state. The final decision on what properties to include lies with the person implementing the describeTo method, who should focus on providing information that is useful for understanding the component's configuration and state.

Example implementation:

 public void describeTo(ComponentDescriptor descriptor) {
     descriptor.describeProperty("name", this.name);
     descriptor.describeProperty("enabled", this.enabled);
     descriptor.describeProperty("configuration", this.configuration); // A nested component
     descriptor.describeProperty("handlers", this.eventHandlers);      // A collection
 }
 

Specified by:

describeTo in interface DescribableComponent

Parameters:

descriptor - The component descriptor to describe this DescribableComponentn its properties in.

evolve

public E evolve(E entity,
 EventMessage event,
 ProcessingContext context)

Description copied from interface: EntityEvolver

Evolve the given entity by applying the given event to it.

Specified by:

evolve in interface EntityEvolver<E>

Parameters:

entity - The current entity to evolve with the given event.

event - The event that might adjust the entity.

context - The context within which to evolve the entity by the given event.

Returns:

The evolved entity based on the given event, or the same entity when nothing happened.

entityType

public Class<E> entityType()

Description copied from interface: EntityMetamodel

Returns the Class of the entity this metamodel describes.

Specified by:

entityType in interface EntityMetamodel<E>

Returns:

The Class of the entity this metamodel describes.