EventAdapter
An EventAdapter is both a WriteEventAdapter and a ReadEventAdapter. Facility to convert from and 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
-
adapting incoming events in any way before persisting them by the journal
- Source:
- EventAdapter.scala
Value members
Inherited methods
Convert a event from its journal model to the applications domain model.
Convert a event from its journal model to the applications domain model.
One event may be adapter into multiple (or none) events which should be delivered to the akka.persistence.PersistentActor. Use the specialised akka.persistence.journal.EventSeq#single method to emit exactly one event, or akka.persistence.journal.EventSeq#empty in case the adapter is not handling this event. Multiple EventAdapter instances are applied in order as defined in configuration and their emitted event seqs are concatenated and delivered in order to the PersistentActor.
- Value parameters:
- event
event to be adapted before delivering to the PersistentActor
- manifest
optionally provided manifest (type hint) in case the Adapter has stored one for this event,
""if none
- Returns:
sequence containing the adapted events (possibly zero) which will be delivered to the PersistentActor
- Inherited from:
- ReadEventAdapter
- Source:
- EventAdapter.scala
Return the manifest (type hint) that will be provided in the fromJournal method.
Use "" if manifest is not needed.
Return the manifest (type hint) that will be provided in the fromJournal method.
Use "" if manifest is not needed.
- Inherited from:
- WriteEventAdapter
- Source:
- EventAdapter.scala
Convert domain event to journal event type.
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 toJournal adaptation must be an 1-to-1 transformation.
It is not allowed to drop incoming events during the toJournal adaptation.
- Value 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
- Inherited from:
- WriteEventAdapter
- Source:
- EventAdapter.scala