t

akka.persistence.journal

WriteEventAdapter

trait WriteEventAdapter extends AnyRef

Facility 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
Source
EventAdapter.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
EventAdapter, IdentityEventAdapter
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Inherited
  1. WriteEventAdapter
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. Protected

Abstract Value Members

  1. abstract def manifest(event: Any): String

    Return the manifest (type hint) that will be provided in the fromJournal method.

    Return the manifest (type hint) that will be provided in the fromJournal method. Use "" if manifest is not needed.

  2. abstract def toJournal(event: Any): Any

    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.

    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