README.md

Upcasters

This module's intention is to give insights on how to create an upcaster and how to test it. This example uses a Json serializer.

The FlightDelayedEvent is used as example. The original (null) revision looks like this:

{
  "arrivalTime": "2021-05-27T15:06:10.629267",
  "flightId": "KL123",
  "origin": "LAX",
  "destination": "LON"
}

Then a new requirement popped up to put the origin and destination into a separate object called leg. Please note, that this is just an example, and we do recommend keeping your event structure as flat as possible. The upcasted event should look like this:

{
  "arrivalTime": "2021-05-27T15:06:10.629267",
  "flightId": "KL123",
  "leg": {
    "origin": "LAX",
    "destination": "LON"
  }
}

You can find the implementation of the upcaster in the FlightDelayedEventUpcaster. The implementation of the test can be found here

To get this upcaster invoked on the event handler it should be added to the EventUpcasterChainFactory or annotate it as a Spring component together with an Order annotation.