Package akka.persistence.journal
Interface WriteEventAdapter
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- All Known Subinterfaces:
EventAdapter
- All Known Implementing Classes:
IdentityEventAdapter$
public interface WriteEventAdapterFacility to convert to specialised data models, as may be required by specialized persistence Journals.Typical use cases include (but are not limited to):
- adding metadata, a.k.a. "tagging" - by wrapping objects into tagged counterparts
- manually converting to the Journals storage format, such as JSON, BSON or any specialised binary format
- splitting up large events into sequences of smaller ones
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description java.lang.Stringmanifest(java.lang.Object event)Return the manifest (type hint) that will be provided in thefromJournalmethod.java.lang.ObjecttoJournal(java.lang.Object event)Convert domain event to journal event type.
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Method Detail
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manifest
java.lang.String manifest(java.lang.Object event)
Return the manifest (type hint) that will be provided in thefromJournalmethod. Use""if manifest is not needed.
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toJournal
java.lang.Object toJournal(java.lang.Object event)
Convert domain event to journal event type.Some journal may require a specific type to be returned to them, for example if a primary key has to be associated with each event then a journal may require adapters to return
com.example.myjournal.EventWithPrimaryKey(event, key).The
toJournaladaptation must be an 1-to-1 transformation. It is not allowed to drop incoming events during thetoJournaladaptation.- Parameters:
event- the application-side domain event to be adapted to the journal model- Returns:
- the adapted event object, possibly the same object if no adaptation was performed
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