Package org.axonframework.modelling.entity

Interface EntityMetamodel<E>

Type Parameters:

E - The type of the entity supported by this metamodel.

All Superinterfaces:

DescribableComponent, EntityEvolver<E>

All Known Implementing Classes:

AnnotatedEntityMetamodel, ConcreteEntityMetamodel, PolymorphicEntityMetamodel

public interface EntityMetamodel<E>
extends EntityEvolver<E>, DescribableComponent

The messaging metamodel of entity type E, containing the information needed to handle commands and events. An EntityMetamodel can be created through the builder by using the forEntityType(Class) method. The metamodel can then be used to handle commands and events for an entity. If the entity already exists, the handleInstance(org.axonframework.messaging.commandhandling.CommandMessage, E, org.axonframework.messaging.core.unitofwork.ProcessingContext) method should be used to handle commands for the entity. If the entity is new, the handleCreate(org.axonframework.messaging.commandhandling.CommandMessage, org.axonframework.messaging.core.unitofwork.ProcessingContext) method should be used to handle commands for creating the entity.

Since:

5.0.0

Author:

Mitchell Herrijgers

Method Summary

Modifier and Type	Method	Description
Class<E>	entityType()	Returns the Class of the entity this metamodel describes.
static <E> EntityMetamodelBuilder<E>	forEntityType(Class<E> entityType)	Starts a new EntityMetamodelBuilder for the given entity type.
static <E> PolymorphicEntityMetamodelBuilder<E>	forPolymorphicEntityType(Class<E> entityType)	Starts a new PolymorphicEntityMetamodelBuilder for the given entity type.
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 interface org.axonframework.common.infra.DescribableComponent

describeTo

Methods inherited from interface org.axonframework.modelling.EntityEvolver

evolve

Method Details

forEntityType

@Nonnull
static <E> EntityMetamodelBuilder<E> forEntityType(Class<E> entityType)

Starts a new EntityMetamodelBuilder for the given entity type. The builder can be used to add command handlers and child entities to the metamodel.

Type Parameters:

E - The type of the entity to create a metamodel for.

Parameters:

entityType - The type of the entity to create a metamodel for.

Returns:

A new EntityMetamodelBuilder for the given entity type.

forPolymorphicEntityType

@Nonnull
static <E> PolymorphicEntityMetamodelBuilder<E> forPolymorphicEntityType(@Nonnull
 Class<E> entityType)

Starts a new PolymorphicEntityMetamodelBuilder for the given entity type. The builder can be used to add command handlers and child entities to the metamodel, specifically for polymorphic entities. The builder also supports adding concrete entity types that extend the given entity type, through PolymorphicEntityMetamodelBuilder.addConcreteType(EntityMetamodel). The required concrete metamodel can be created with forEntityType(Class).

Type Parameters:

E - The type of the entity to create a metamodel for.

Parameters:

entityType - The type of the entity to create a metamodel for.

Returns:

A new PolymorphicEntityMetamodelBuilder for the given entity type.

entityType

@Nonnull
Class<E> entityType()

Returns the Class of the entity this metamodel describes.

Returns:

The Class of the entity this metamodel describes.

handleCreate

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

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 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.

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

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

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 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.

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.

supportedCreationalCommands

@Nonnull
Set<QualifiedName> supportedCreationalCommands()

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 handleCreate(org.axonframework.messaging.commandhandling.CommandMessage, org.axonframework.messaging.core.unitofwork.ProcessingContext) method.

Returns:

A set of QualifiedName instances representing the supported command names.

supportedInstanceCommands

@Nonnull
Set<QualifiedName> supportedInstanceCommands()

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 handleInstance(org.axonframework.messaging.commandhandling.CommandMessage, E, org.axonframework.messaging.core.unitofwork.ProcessingContext) method.

Returns:

A set of QualifiedName instances representing the supported command names.

supportedCommands

@Nonnull
Set<QualifiedName> supportedCommands()

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

Returns:

A set of QualifiedName instances representing the supported command names.