How to make DataLoaders fun in Schema codes works in Spring

[hantsy]

In the DataLoaders, there is an example to demo the DataLoaders.

class User(val id: ID) {
    @GraphQLDescription("Get the users friends using data loader")
    fun getFriends(dataFetchingEnvironment: DataFetchingEnvironment): CompletableFuture<List<User>> {
        return dataFetchingEnvironment.getValueFromDataLoader("FriendsDataLoader", id)
    }
}

But how to make it work in a Spring boot application?

I tried to define the Post schema like this.

data class Post(
    val id: UUID?,
    @UpperCase
    val title: String,
    val content: String?,
    val status: String? = null,
    val createdAt: LocalDateTime?,
    val authorId: UUID? = null,
) {
    lateinit var author: Author
    lateinit var comments: List<Comment>
    fun getComments(environment: DataFetchingEnvironment): CompletableFuture<List<Comment>> {
        return environment.getValueFromDataLoader(CommentsDataLoader.name, id)
    }

    fun getAuthor(environment: DataFetchingEnvironment): CompletableFuture<Author> {
        return environment.getValueFromDataLoader(AuthorsDataLoader.name, authorId)
    }
}

And define the DataLoaders like this.

@Component
class AuthorsDataLoader(val authorService: AuthorService) : KotlinDataLoader<UUID, Author> {
    companion object {
        const val name = "AuthorsDataLoader"
    }

    override val dataLoaderName = name

    override fun getDataLoader(): DataLoader<UUID, Author> {
        return DataLoaderFactory.newDataLoader { keys, environment ->
            loaderScope.future {
                authorService.getAuthorByIdIn(keys).toList()
            }
        }
    }
}


@Component
class CommentsDataLoader(val postService: PostService) : KotlinDataLoader<UUID, List<Comment>> {
    companion object {
        private val log = LoggerFactory.getLogger(CommentsDataLoader::class.java)
        const val name = "CommentsDataLoader"
    }

    override val dataLoaderName = AuthorsDataLoader.name

    override fun getDataLoader(): DataLoader<UUID, List<Comment>> {
        return DataLoaderFactory.newMappedDataLoader { keys, environment ->
            loaderScope.future {
                val comments = postService.getCommentsByPostIdIn(keys).toList()
                val mappedComments: MutableMap<UUID, List<Comment>> = mutableMapOf()
                keys.forEach { mappedComments[it] = comments.filter { c -> c.postId == it } }
                log.info("mapped comments: {}", mappedComments)
                mappedComments
            }
        }
    }
}

The above codes does not works.

[dariuszkuc]

For completeness -> this seems like a duplicate of #1533