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I guess I'll try my luck here, as it doesn't fit in a channel and is imo not exactly a beginner question. I am trying to develop a client for the deezer api. I want to do it, using both retrofit and moshi. As you can see here (<https://developers.deezer.com/api/explorer?url=album/302127>), Deezer has the issue, that it wraps every array in a object called "data". I try to unwrap that unnecessary data-object to get a nice and clean api. This is the code I have so far: (<https://pastebin.com/wTRRZn8E>). Unfortunately it does crash with the following exception: <https://pastebin.com/6hjVGECP> I hope you can help me out :slightly_smiling_face:

Assuming you're trying to use generics with the Moshi KotlinJsonAdapterFactory, it's a known limitation.
<https://github.com/square/moshi/issues/309>

Maybe consider installing a Java JsonAdapter.Factory like the one here <https://github.com/square/moshi/blob/master/examples/src/main/java/com/squareup/moshi/recipes/Unwrap.java> and apply its Enveloped qualifier to types you want unwrapped?

Thank you so much for your tips :slightly_smiling_face: I'll try :slightly_smiling_face:

<@U5G4USJPQ> For fun, I parsed it with Klaxon and the following works just fine:
```
    data class Track(val id: Long, val title: String)
    data class TrackData(val data: List&lt;Track&gt;)
    data class Album(val id: Int, val title: String, val link: String, val cover_big: String, val duration: Int,
            val rating: Int, val tracks: TrackData)

    fun t() {
        val json =
            URL("<http://api.deezer.com/album/53227232>").openConnection().inputStream.reader().readText()
        Klaxon().parse&lt;Album&gt;(json)?.let {
            println("Album: ${it.title} ${it.tracks.data.size} tracks")
        }
    }
```
Note that I adapted the data classes to match the shape of the JSON more closely. No need for an adapter.

Well, if you're doing that without the Kotlin box generic type, Moshi will work fine, too, and no need for an adapter.

<@U0DQC8QHM> Not sure what you mean, there is a generic type up there (see the `parse` invocation)

Kotlin's reflection has a few added features over Java's which allows for some cool things in a Kotlin-based JSON parser

my point is that he was asking about custom generic types, like asking Moshi for an adapter for `Box&lt;T&gt;`.
which doesn't work in the KotlinJsonAdapter in Moshi right now.

without custom generic types, there's no need for anything special in Moshi.

from your code:

```
val adapter = Moshi.Builder().build().adapter&lt;Album&gt;(Album::class.java)
    URL("<http://api.deezer.com/album/53227232>").openConnection().inputStream.use {
      val album = adapter.fromJson(JsonReader.of(Okio.buffer(Okio.source(it))))
      println(album)
    }
```
works fine.

Yup. Note that you need the extra class parameter `Album::class.java`.

I don't see any `Box` in <https://pastebin.com/wTRRZn8E>