How to parse just part of JSON with Klaxon? - json

Question

I'm trying to parse some JSON to kotlin objects. The JSON looks like:
{
data: [
{ "name": "aaa", "age": 11 },
{ "name": "bbb", "age": 22 },
],
otherdata : "don't need"
}
I just need to data part of the entire JSON, and parse each item to a User object:
data class User(name:String, age:Int)
But I can't find an easy way to do it.

Answer 1

Here's one way you can achieve this
import com.beust.klaxon.Klaxon
import java.io.StringReader
val json = """
{
"data": [
{ "name": "aaa", "age": 11 },
{ "name": "bbb", "age": 22 },
],
"otherdata" : "not needed"
}
""".trimIndent()
data class User(val name: String, val age: Int)
fun main(args: Array<String>) {
val klaxon = Klaxon()
val parsed = klaxon.parseJsonObject(StringReader(json))
val dataArray = parsed.array<Any>("data")
val users = dataArray?.let { klaxon.parseFromJsonArray<User>(it) }
println(users)
}
This will work as long as you can fit the whole json string in memory. Otherwise you may want to look into the streaming API: https://github.com/cbeust/klaxon#streaming-api