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kotlinlang

Hey everyone! I have a endpoint that returns replies of a post, and the structure is something like that:
```data class PostReply(
  val author: String,
  val body: String,
  val replies: List&lt;PostReply&gt; // can be infinitely deep
)```
I’ve created one regular data class, and another with serialized annotations. But I cannot think a good way on how to map `replies` recursively. I tried that but didn’t work:
```fun PostRepliesResponse.toModel() = PostReplies(
    //...
    replies = replies.map { reply -&gt; reply.toModel() }
)```
Can you guys help me?

Did it error out or did it just end up with an empty list of replies?

Also can you post signature of the `PostReplies` and `PostRepliesResponse` classes?

Captura de Tela 2022-11-27 às 18.02.18.png

The classes are equal, but PostRepliesResponse has `@SerializedName("")` on fields

What does the `.toModel()` look like on the `PostReply` class?

`.toModel()` is a extension to map from `PostRepliesResponse`  to `PostReplies`

And if I manage this to work, I’m gonna create another like `PostReplies.toResponse()`

Well the sections of `replies.map { reply -&gt; reply.toModel() }` is trying to call a `toModel` as well, but it's called on a separate type, what is the types of the `replies` list here? It's hard for me to tell without more context, but it seems like we only defined a single `toModel` extension on the top level model but I'm not seeing where we defined a `toModel` extension on the inner reply types

Thats the problem I’m trying to solve! The `replies` field is a list of `PostReplies` . Each reply have a replies field of the same time

What I’m trying to do is call `.toModel()`  recursively

Ah okay, so off the top of my head I'm thinking
```fun PostReplies.toModel(): List&lt;PostReplies&gt; {
  if (replies.isNotEmpty()) {
    replies.map { reply -&gt; reply.toModel() }
  } else {
    emptyList&lt;PostReplies&gt;()
  }
}```

Because we essentially just want it to keep building out that base list recursively and stop at the end if we find no more

The more I look at my solution the more I'm doubting it though :sweat_smile:

```fun PostRepliesResponse.toModel() = PostReplies(
    id = id,
    ownerUsername = ownerUsername,
    body = body,
    tabcoins = tabcoins,
    repliesAmount = repliesAmount,
    replies = replies.toModel()
)

fun List&lt;PostRepliesResponse&gt;.toModel(): List&lt;PostReplies&gt; {
    return this.map {
        PostReplies(
            id = it.id,
            ownerUsername = it.ownerUsername,
            body = it.body,
            tabcoins = it.tabcoins,
            repliesAmount = it.repliesAmount,
            replies = it.replies.toModel()
        )
    }
}```


feels weird, but I think is gonna work :sweat_smile:

ah yes that looks much better, that actually includes the model conversion piece

May need to be careful of any stackoverflows in the future with that recursive model though :sweat_smile:

<@U04BV5DL0CC> | yup! Some how worked :melting_face: