Package akka.persistence.typed.state.scaladsl

Class ChangeEventHandler$

java.lang.Object

akka.persistence.typed.state.scaladsl.ChangeEventHandler$

public class ChangeEventHandler$
extends java.lang.Object

API May Change

Field Summary

Fields

Modifier and Type	Field	Description
static ChangeEventHandler$	MODULE$	Static reference to the singleton instance of this Scala object.

Constructor Summary

Constructors

Constructor	Description
ChangeEventHandler$()

Method Summary

Modifier and Type	Method	Description
<Command,State,ChangeEvent> ChangeEventHandler<Command,State,ChangeEvent>	apply(scala.Function3<State,State,Command,ChangeEvent> updateHandler, scala.Function2<State,Command,ChangeEvent> deleteHandler)	Define these handlers in the DurableStateBehavior.withChangeEventHandler(akka.persistence.typed.state.scaladsl.ChangeEventHandler<Command, State, ChangeEvent>) to store additional change event when the state is updated.

Methods inherited from class java.lang.Object

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

Field Detail

MODULE$

public static final ChangeEventHandler$ MODULE$

Static reference to the singleton instance of this Scala object.

Constructor Detail

ChangeEventHandler$

public ChangeEventHandler$()

Method Detail

apply

public <Command,State,ChangeEvent> ChangeEventHandler<Command,State,ChangeEvent> apply(scala.Function3<State,State,Command,ChangeEvent> updateHandler,
                                                                                                               scala.Function2<State,Command,ChangeEvent> deleteHandler)

Define these handlers in the DurableStateBehavior.withChangeEventHandler(akka.persistence.typed.state.scaladsl.ChangeEventHandler<Command, State, ChangeEvent>) to store additional change event when the state is updated. The event can be used in Projections.

The updateHandler and deleteHandler are invoked after the ordinary command handler. Be aware of that if the state is mutable and modified by the command handler the previous state parameter of the updateHandler will also include the modification, since it's the same instance. If that is a problem you need to use immutable state and create a new state instance when modifying it in the command handler.

Parameters:

updateHandler - Function that given the previous and new state creates the change event to be stored when the DurableState is updated.

deleteHandler - Function that given the previous state creates the change event to be stored when the DurableState is deleted.