How to parse response with jackson using ktor? - kotlin

Question

I have this dependencies:
implementation("io.ktor:ktor-server-core:$ktor_version")
implementation("io.ktor:ktor-jackson:$ktor_version")
implementation("io.ktor:ktor-server-netty:$ktor_version")
implementation("ch.qos.logback:logback-classic:$logback_version")
implementation("io.ktor:ktor-client-cio:$ktor_version")
implementation("io.ktor:ktor-client-json:$ktor_version")
And this settings of ktor server:
fun Application.configureHTTP() {
install(DefaultHeaders)
install(CallLogging)
install(AutoHeadResponse)
install(Routing)
install(ContentNegotiation) {
register(ContentType.Application.Json, JacksonConverter())
jackson {
enable(SerializationFeature.INDENT_OUTPUT)
disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
writerWithDefaultPrettyPrinter()
}
}
install(CORS) {
method(HttpMethod.Options)
method(HttpMethod.Put)
method(HttpMethod.Delete)
method(HttpMethod.Patch)
header(HttpHeaders.Authorization)
header("MyCustomHeader")
// allowCredentials = true
anyHost() // #TODO: Don't do this in production if possible. Try to limit it.
}
}
I'd like to get joke's text about Chuck Norris, so I made this data classes:
data class ChuckNorrisJoke(
val type: String,
val value: Map<Any, Any>
)
data class JokeContent(
val id: Long,
val joke: String,
val categories: List<String>
)
And eventually this is my function for getting joke:
val client = HttpClient(CIO) {
install(JsonFeature)
}
suspend fun getChuckNorrisJoke(): ChuckNorrisJoke {
return client
.get("http://api.icndb.com/jokes/random")
}
When I call the method, I get this error:
Exception in thread "main" java.lang.ExceptionInInitializerError
Caused by: java.lang.IllegalStateException: Fail to find serializer. Consider to add one of the following dependencies:
- ktor-client-gson
- ktor-client-json
- ktor-client-serialization
at io.ktor.client.features.json.DefaultJvmKt.defaultSerializer(DefaultJvm.kt:14)
at io.ktor.client.features.json.JsonFeature$Feature.prepare(JsonFeature.kt:130)
at io.ktor.client.features.json.JsonFeature$Feature.prepare(JsonFeature.kt:125)
at io.ktor.client.HttpClientConfig$install$3.invoke(HttpClientConfig.kt:77)
at io.ktor.client.HttpClientConfig$install$3.invoke(HttpClientConfig.kt:74)
at io.ktor.client.HttpClientConfig.install(HttpClientConfig.kt:97)
at io.ktor.client.HttpClient.<init>(HttpClient.kt:172)
at io.ktor.client.HttpClient.<init>(HttpClient.kt:81)
at io.ktor.client.HttpClientKt.HttpClient(HttpClient.kt:43)
at com.example.ApplicationKt.<clinit>(Application.kt:109)
Can't understand how to set HttpClient correctly.

Answer 1

The implementation("io.ktor:ktor-jackson:$ktor_version") dependency declaration is for the server. You need to declare one for the client: implementation "io.ktor:ktor-client-jackson:$ktor_version". You can find more information here.