Hey everyone! I have a endpoint that returns replies of a post, and the structure is something like ...

# android

[Daniel De Jesus Rodrigues]

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<PostReply> // 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 -> reply.toModel() }
)

Can you guys help me?

[Josh Eldridge]

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?

[Daniel De Jesus Rodrigues]

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

[Daniel De Jesus Rodrigues]

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

[Josh Eldridge]

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

[Daniel De Jesus Rodrigues]

Does not

[Daniel De Jesus Rodrigues]

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

[Daniel De Jesus Rodrigues]

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

[Josh Eldridge]

Well the sections of replies.map { reply -> 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

[Daniel De Jesus Rodrigues]

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

[Daniel De Jesus Rodrigues]

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

[Josh Eldridge]

Ah okay, so off the top of my head I'm thinking

fun PostReplies.toModel(): List<PostReplies> {
  if (replies.isNotEmpty()) {
    replies.map { reply -> reply.toModel() }
  } else {
    emptyList<PostReplies>()
  }
}

[Josh Eldridge]

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

[Josh Eldridge]

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

[Daniel De Jesus Rodrigues]

I think i got it

[Daniel De Jesus Rodrigues]

I created another extension

[Daniel De Jesus Rodrigues]

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

fun List<PostRepliesResponse>.toModel(): List<PostReplies> {
    return this.map {
        PostReplies(
            id = it.id,
            ownerUsername = it.ownerUsername,
            body = it.body,
            tabcoins = it.tabcoins,
            repliesAmount = it.repliesAmount,
            replies = it.replies.toModel()
        )
    }
}

[Daniel De Jesus Rodrigues]

feels weird, but I think is gonna work 😅

[Josh Eldridge]

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

[Josh Eldridge]

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

[Daniel De Jesus Rodrigues]

What do you mean? 😂

[Daniel De Jesus Rodrigues]

@Josh Eldridge | yup! Some how worked 🫠

[Josh Eldridge]

Sweet!