We’ve ended up with following serializer for Event Store persistence:
import akka.persistence.PersistentImpl;
import akka.persistence.PersistentRepr;
import akka.persistence.eventstore.EventStoreSerializer;
import org.ad.domain.CampaignCreated;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import eventstore.Event;
import eventstore.EventData;
import eventstore.j.EventDataBuilder;
import scala.Option;
import java.io.IOException;
import static akka.actor.ActorRef.noSender;
public class JsonSerializer implements EventStoreSerializer {
@Override
public int identifier() {
return 10023;
}
@Override
public byte[] toBinary(Object o) {
ObjectMapper mapper = new ObjectMapper();
try {
String s = mapper.writeValueAsString(o);
return s.getBytes();
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
@Override
public boolean includeManifest() {
return true;
}
@Override
public Object fromBinary(byte[] bytes, Option<Class<?>> classOption) {
return fromBinary(bytes, classOption.get());
}
@Override
public Object fromBinary(byte[] bytes) {
return null;
}
@Override
public Object fromBinary(byte[] bytes, Class<?> aClass) {
ObjectMapper mapper = new ObjectMapper();
try {
return mapper.readValue(bytes, aClass);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
public EventData toEvent(Object o) {
PersistentImpl obj = (PersistentImpl) o;
EventDataBuilder eventDataBuilder = new EventDataBuilder(obj.payload().getClass().getName());
eventDataBuilder.jsonData(new String(toBinary(obj.payload())));
eventDataBuilder.jsonMetadata(obj.payload().getClass().getName());
return eventDataBuilder.build();
}
@Override
public Object fromEvent(Event event, Class<?> aClass) {
Object result = null;
try {
result = fromBinary(event.data().data().value().toArray(), Class.forName(event.data().eventType()));
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
PersistentRepr persistentRepr = new PersistentImpl(
result,
event.number().value(),
event.streamId().value(),
false,
null,
noSender()
);
return persistentRepr;
}
}
``
We have several questions:
- Method fromBinary(byte[] bytes) always returns null. Is it safe to assume, that it will not ever be called?
- We are persisting our own objects, but not PersistentRepr. This leads us to recrecreating PersistentRepr each time with dummy parameters. Is it ok? Will we encounter any problems?
Thank you in advance!
