How do I parse a response with Ktor

user_5305817 0
Viewed 4222

I'm trying to do a Get call with Ktor in a multiplatform project. This is the code:

private val client = HttpClient()

fun myCall(callback: (List<Film>) -> Unit) {

    viewModelScope.launch {
        val result:List<Film> = client.get {
            url("https://data.sfgov.org/resource/wwmu-gmzc.json")
        }
        callback(result)
    }
}

Every time I make this request the application closes and I don't receive any message that gives me a clue what's going on. If instead of putting a list Film as the result type I put String then it works and I receive a list of movies, but I want to parse it to my own objects and I am unable.

Is there something wrong with the call?

ktor kotlin-multiplatform kotlin json
2 Answers

For the Ktor http client to deserialize to your custom object, you would need to install JsonFeature while creating your http client, which would need the io.ktor:ktor-client-json dependency added.

val client = HttpClient {
   install(JsonFeature)
}

Then depending on whichever serializer you want to use (Ktor supports Gson, Jackson and Kotlinx.Serialization), you need to add the dependency of the respective serializer. For eg, if you want to use Gson, you need to add the dependency for io.ktor:ktor-client-gson. Then your API response would get deserialized to your List<Film> object.

val result: List<Film> = client.get {
   url("https://data.sfgov.org/resource/wwmu-gmzc.json")
}

More on the above in the Ktor documentation

user_98403180

For your result, you could also try using HttpResponse as a type.

And I think, you then still have to explicitly use the library (e.g. Gson) to parse the api-response, e.g.

val result: HttpResponse = client.get("https://data.sfgov.org/resource/wwmu-gmzc.json")
val parsedResponseBody = Gson().fromJson(result.readText(), Films::class.java)

readText() is an extension function on HttpResponse and returns the content (the response body) as a string.

Your data class should then somehow look like:

data class Films(val films: List<Film>) {
    data class Film(*...*)
}
user_120740920
Related