Transform Header and payload to Json nodes - spring-integration

Question

I am trying to enrich payload with some Headers keys and convert to a json structure like that:
{
"Header": { ["key" : "value", "key2": "value"]}
"Payload": { "attribute" : "value" }
}
My gateway is configured like this:
#MessagingGateway
public static interface MailService {
#Gateway(requestChannel = "mail.input")
void sendMail(String body, #Headers Map<String,String> headers);
}
Here is my flow:
#Bean
public IntegrationFlow errorFlow(){
return IntegrationFlows.from(recoveryChannel())
.transform("payload.failedMessage")
.enrichHeaders(c -> c.header(FileHeaders.FILENAME, "emailErrors.json"))
.handle(this.fileOutboundAdapter())
.get();
}
How could I solve this issue?
Thanks.

Answer 1

To convert the whole message to the JSON, you should do something like this:
.handle((p, h) -> MessageBuilder.withPayload(new GenericMessage<>(p, h)))
.transform(Transformers.toJson())
The trick is like Transformers.toJson() doesn't care about headers and transforms only payload. So, we have to hack it a bit placing the whole message to the payload.
Since ServiceActivator (ground floor of the .handle()) returns message as is if the result is Message<?> , we don't have choice unless provide MessageBuilder and Transformers.toJson() will have all the info for your use-case.

Answer 2

#SpringBootApplication
public class So41223173Application {
public static void main(String[] args) {
ConfigurableApplicationContext context = SpringApplication.run(So41223173Application.class, args);
context.getBean("flow.input", MessageChannel.class)
.send(new ErrorMessage(new MessagingException(new GenericMessage<>(new Foo()))));
context.close();
}
#Bean
public IntegrationFlow flow() {
return f -> f.transform("payload.failedMessage")
.enrichHeaders(c -> c.header("foo", "bar"))
.transform(toMap(), "transform")
.transform(Transformers.toJson())
.handle(m -> System.out.println(m.getPayload()));
}
#Bean
public Transformer toMap() {
return new AbstractTransformer() {
#Override
protected Object doTransform(Message<?> message) throws Exception {
Map<String, Object> map = new LinkedHashMap<>();
Map<String, Object> headers = new LinkedHashMap<>(message.getHeaders());
headers.remove(MessageHeaders.ID);
headers.remove(MessageHeaders.TIMESTAMP);
map.put("headers", headers);
map.put("payload", message.getPayload());
return map;
}
};
}
public static class Foo {
String bar = "bar";
public String getBar() {
return this.bar;
}
public void setBar(String bar) {
this.bar = bar;
}
}
}
result
{"headers":{"foo":"bar"},"payload":{"bar":"bar"}}