com.example.hello.impl

Class HelloEntity

java.lang.Object

com.lightbend.lagom.javadsl.persistence.PersistentEntity<HelloCommand,HelloEvent,HelloState>

com.example.hello.impl.HelloEntity

public class HelloEntity
extends com.lightbend.lagom.javadsl.persistence.PersistentEntity<HelloCommand,HelloEvent,HelloState>

This is an event sourced entity. It has a state, HelloState, which stores what the greeting should be (eg, "Hello Alice").

Event sourced entities are interacted with by sending them commands. This entity supports two commands, a HelloCommand.UseGreetingMessage command, which is used to change the greeting, and a HelloCommand.Hello command, which is a read only command which returns a greeting to the name specified by the command.

Commands get translated to events, and it's the events that get persisted by the entity. Each event will have an event handler registered for it, and an event handler simply applies an event to the current state. This will be done when the event is first created, and it will also be done when the entity is loaded from the database - each event will be replayed to recreate the state of the entity.

This entity defines one event, the HelloEvent.GreetingMessageChanged event, which is emitted when a HelloCommand.UseGreetingMessage command is received.

Nested Class Summary

Nested classes/interfaces inherited from class com.lightbend.lagom.javadsl.persistence.PersistentEntity

com.lightbend.lagom.javadsl.persistence.PersistentEntity.Behavior, com.lightbend.lagom.javadsl.persistence.PersistentEntity.Behavior$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.BehaviorBuilder, com.lightbend.lagom.javadsl.persistence.PersistentEntity.BehaviorBuilderImpl, com.lightbend.lagom.javadsl.persistence.PersistentEntity.CommandContext<R>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.InvalidCommandException, com.lightbend.lagom.javadsl.persistence.PersistentEntity.InvalidCommandException$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.Persist<B extends Event>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistAll<B extends Event>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistAll$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistException, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistException$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistNone<B extends Event>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistNone$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistOne<B extends Event>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.PersistOne$, com.lightbend.lagom.javadsl.persistence.PersistentEntity.ReadOnlyCommandContext<R>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.ReplyType<R>, com.lightbend.lagom.javadsl.persistence.PersistentEntity.UnhandledCommandException, com.lightbend.lagom.javadsl.persistence.PersistentEntity.UnhandledCommandException$

Constructor Summary

Constructors

Constructor and Description
HelloEntity()

Method Summary

Modifier and Type	Method and Description
com.lightbend.lagom.javadsl.persistence.PersistentEntity.Behavior	initialBehavior(java.util.Optional<HelloState> snapshotState) An entity can define different behaviours for different states, but it will always start with an initial behaviour.

Methods inherited from class com.lightbend.lagom.javadsl.persistence.PersistentEntity

behavior, Behavior, com$lightbend$lagom$javadsl$persistence$PersistentEntity$$persistNone, entityId, entityTypeName, internalSetCurrentBehavior, internalSetEntityId, newBehavior, newBehaviorBuilder, PersistAll, PersistNone, PersistOne, recoveryCompleted, state

Methods inherited from class java.lang.Object

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

Constructor Detail

HelloEntity

public HelloEntity()

Method Detail

initialBehavior

public com.lightbend.lagom.javadsl.persistence.PersistentEntity.Behavior initialBehavior(java.util.Optional<HelloState> snapshotState)

An entity can define different behaviours for different states, but it will always start with an initial behaviour. This entity only has one behaviour.

Specified by:

initialBehavior in class com.lightbend.lagom.javadsl.persistence.PersistentEntity<HelloCommand,HelloEvent,HelloState>