[FIXED] Ktor with Spring boot WebFlux web api

Issue

I have a simple Spring Boot WebFlux api and I am trying to use Ktor to call it.

Here is my controller

@RestController
@RequestMapping("api/v1")
class TestController {

    @RequestMapping(method = [RequestMethod.GET], value = ["/values"], produces = [MediaType.TEXT_EVENT_STREAM_VALUE])
    fun sayHello(@RequestParam(value = "name") name:String): Flux<Example> {
        return Flux.interval(Duration.ofSeconds(1))
            .map { Example(number = generateNumber()) }
            .share()
    }

    fun generateNumber(): Int{
        return ThreadLocalRandom.current().nextInt(100)
    }
}

It just returns an object with a number every second

Now on the client side is where I want to use Ktor to get the data but I am unsure what to do. Reading the docs it looks like Scoped streaming is what I need but I am not sure how to get it to work with my controller

Here is the client code I have so far.

suspend fun getData(): Flow<Example> {
        return flow {
            val client = HttpClient()
            client.get<HttpStatement>("http://192.168.7.24:8080/api/v1/values?name=hello").execute{
        val example = it.receive<Example>()
        emit(example)
    }
        }
    }

When I try to make the call on the Android client I get this error

NoTransformationFoundException: No transformation found: class io.ktor.utils.io.ByteBufferChannel (Kotlin reflection is not available)

So it looks like I cant just serialize the stream into my object so how do I serialize ByteReadChannel to an object?

This is my first time trying out spring and ktor

Solution

To be able to serialize the data into an object you need to do t manually by reading the data into a byte array

 client.get<HttpStatement>("http://192.168.7.24:8080/api/v1/values?name=hello").execute{
        val channel = it.receive<ByteReadChannel>()
        val byteArray = ByteArray(it.content.availableForRead)
        channel.readAvailable(byteArray,0,byteArray.size)
        val example:Example = Json.parse<Example>(stringFromUtf8Bytes(byteArray))
    }

Answered By - tyczj