How to get list from response in Kotlin - json

Question

I have this API that returns a list as a response:
https://animension.to/public-api/search.php?search_text=&season=&genres=&dub=&airing=&sort=popular-week&page=2
This returns a response string in list format like this
[["item", 1, "other item"], ["item", 2, "other item"]]
How do I convert this so that I can use it as a list, not a string data type?

Answer 1

One way is to use Kotlinx Serialization. It doesn't have direct support for tuples, but it's easy to parse the input as a JSON array, then manually map to a specific data type (if we make some assumptions).
First add a dependency on Kotlinx Serialization.
// build.gradle.kts
plugins {
kotlin("jvm") version "1.7.10"
kotlin("plugin.serialization") version "1.7.10"
// the KxS plugin isn't needed, but it might come in handy later!
}
dependencies {
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.4.0")
}
(See the Kotlinx Serialization README for Maven instructions.)
Then we can use the JSON mapper to parse the result of the API request.
import kotlinx.serialization.json.*
fun main() {
val inputJson = """
[["item", 1, "other item"], ["item", 2, "other item"]]
""".trimIndent()
// Parse, and use .jsonArray to force the results to be a JSON array
val parsedJson: JsonArray = Json.parseToJsonElement(inputJson).jsonArray
println(parsedJson)
// [["item",1,"other item"],["item",2,"other item"]]
}
It's much easier to manually map this JsonArray object to a data class than it is to try and set up a custom Kotlinx Serializer.
import kotlinx.serialization.json.*
fun main() {
val inputJson = """
[["item", 1, "other item"], ["item", 2, "other item"]]
""".trimIndent()
val parsedJson: JsonArray = Json.parseToJsonElement(inputJson).jsonArray
val results = parsedJson.map { element ->
val data = element.jsonArray
// Manually map to the data class.
// This will throw an exception if the content isn't the correct type...
SearchResult(
data[0].jsonPrimitive.content,
data[1].jsonPrimitive.int,
data[2].jsonPrimitive.content,
)
}
println(results)
// [SearchResult(title=item, id=1, description=other item), SearchResult(title=item, id=2, description=other item)]
}
data class SearchResult(
val title: String,
val id: Int,
val description: String,
)
The parsing I've defined is strict, and assumes each element in the list will also be a list of 3 elements.