Outbox message should be in the CloudEvent format

[mcruzdev]

Context

Using the Outbox API:

public Response createWithOutbox(OrderRequest request) {
        Log.info("Receiving request for creating an Order: " + request);

        String uuid = UUID.randomUUID().toString();

        Order order = new Order(uuid,
                request.items().stream().map(i -> new Order.OrderItem(i.id(), i.name(), i.price())).toList());

        /* outbox.yaml: metadata.name */
        ExecuteStateTransactionRequest transactionRequest = new ExecuteStateTransactionRequest("postgres-outbox");

        List<TransactionalStateOperation<?>> ops = new ArrayList<>();

        Map<String, String> metadata = new HashMap<>();
        metadata.put("datacontenttype", "application/json");

        State<Order> state = new State<>(order.id(), order, null, metadata, new StateOptions(Consistency.STRONG, Concurrency.FIRST_WRITE));

        TransactionalStateOperation<Order> upsertOps = new TransactionalStateOperation<>(
                TransactionalStateOperation.OperationType.UPSERT, state);

        ops.add(upsertOps);

        transactionRequest.setOperations(ops);

        dapr.executeStateTransaction(transactionRequest).block();

        Log.info("Event (order.created) sent to 'rabbitmq' and order saved to the database using Outbox pattern");

        return Response
                .ok(new OrderResponse(order.id(), order.status(), order.items().stream()
                        .map(item -> new OrderRequest.OrderItemRequest(item.id(), item.name(), item.price())).toList()))
                .build();
    }

I am facing a wrong behavior, which is not the same as documented here https://docs.dapr.io/developing-applications/building-blocks/pubsub/pubsub-cloudevents/#dapr-generated-cloudevents-example

Actual behavior

{"data":"{\"id\":\"dd1f1122-cb3a-4dc4-8ab6-e16ff6599a61\",\"status\":\"RECEIVED\",\"items\":[{\"id\":1,\"name\":\"Quarkus Stickers\",\"price\":19.99}]}","datacontenttype":"text/plain","id":"outbox-06af412d-e21b-4151-8f25-9c6c7273a95c","pubsubname":"rabbitmq","source":"orders-api","specversion":"1.0","time":"2025-10-22T18:40:26Z","topic":"order.created","traceid":"00-dc2464c8d9432109a3d1f13469aa739a-ed59c9a3d2829220-01","traceparent":"","tracestate":"","type":"com.dapr.event.sent"}

Expected behavior

{"data": { "id": "dd1f1122-cb3a-4dc4-8ab6-e16ff6599a61","status":"RECEIVED","items":[{"id":1,"name":"Quarkus Stickers","price":19.99}]}","datacontenttype":"application/json","id":"outbox-06af412d-e21b-4151-8f25-9c6c7273a95c","pubsubname":"rabbitmq","source":"orders-api","specversion":"1.0","time":"2025-10-22T18:40:26Z","topic":"order.created","traceid":"00-dc2464c8d9432109a3d1f13469aa739a-ed59c9a3d2829220-01","traceparent":"","tracestate":"","type":"com.dapr.event.sent"}

The data field is coming as string not a object, I tried to use cloudevent.datacontentype but without success too.

[mcruzdev]

/assign

[mcruzdev]

It is the same issue reported here dapr/dapr#7113 but for .NET client

[mcruzdev]

@artur-ciocanu @salaboy @cicoyle @siri-varma I think that I found the problem. The gRPC field is bytes, and is mapped to a ByteString on Java side.

gRPC definition: https://github.com/dapr/dapr/blob/7d652ff7e69e106157f527f4fb7a1b0435537d29/dapr/proto/common/v1/common.proto#L112

ByteString.copyFrom: https://github.com/dapr/java-sdk/blob/6e9ee5adc4a7300ae96822264f9be65458aa0880/sdk/src/main/java/io/dapr/client/DaprClientImpl.java#L858C7-L858C57

It transforms the value to a JSON string format instead a JSON object.

One solution that I have in mind is to map this one on the consumer side (in the framework code, before the user code), but it only solves the consumer, if we look into a database, the data is in JSON string too.