Hi. Do you know any library that is in Kotlin and ...

# multiplatform

[Giorgi]

Hi. Do you know any library that is in Kotlin and can search for specific key in a Json and return it? There is a website Im scraping and it's API call returns huge JSON text out of which 99% is useless for me. There is just one Array I need to find and this is how I suffer :

((Json.decodeFromString<JsonObject>(response.bodyAsText())["onResponseReceivedActions"] as JsonArray)[0] as JsonObject)["reloadContinuationItemsCommand"]

If I use JSON to kotlin class plugin then I get 110 different objects and for some reason the code does not compile

[eygraber]

I hope to get to this soon https://github.com/codeniko/JsonPathKt/pull/31

[Giorgi]

Thanks, it looks very promissing, including the PR

[Giorgi]

🚀

[kevin.cianfarini]

If you set kolinx serialization to ignore unknown keys

val json = Json {
  ignorUnknownKeys = true
}

and then write your model as

@Serializable class Response(
  val onResponseReceivedAction: List<SomeType>
)

You should be able to do this

[Casey Brooks]

I never published it as a library, but a while ago I made a little utility for a pure kotlin JsonPointer using kotlinx.serialization `JsonElement`s. It’s not as powerful as JsonPath, but it is simpler and pure-kotlin, plus it also allows a similar syntax for updating the JSON object as well. You’re welcome to copy the sources into your project.

[mbonnin]

I have this that I copy paste in each of my project:

fun JsonElement.toAny(): Any? {...}

inline fun <reified T> Any?.cast() = this as T

val Any?.asMap: Map<String, Any?>
    get() = this.cast()
val Any?.asList: List<Any?>
    get() = this.cast()
val Any?.asString: String
    get() = this.cast()
val Any?.asBoolean: String
    get() = this.cast()
val Any?.asNumber: Number
    get() = this.cast()

Then you can write

Json.decodeFromString(response.text())
   ?.asMap["onResponseReceivedActions"]
   ?.asList[0]
   ?.asMap["reloadContinuationItemsCommand"]

It's not perfect but you don't have to go back all the time to open those cast parenthesis yell at parenthesis

[ephemient]

why? if you just use the extensions already in kotlinx.serialization.json:

Json.decodeFromString<JsonElement>(response.bodyAsText())
    .jsonObject["onResponseReceivedActions"]!!
    .jsonArray[0]
    .jsonObject["reloadContinuationItemsCommand"]!!
    .jsonPrimitive.content

[mbonnin]

Not sure exactly why I liked working with Maps and List better than JsonElement. I guess the .jsonObject vs .asObject got me a bit confused initially and I never questioned this again. Also I'd really like to see this cast<T>() method reach stdlib one day so I'm practicing it 😄

[Mohammed Akram Hussain]

you can use kotlinx serialisation library and create a data class containing only the values you're looking for?

[mbonnin]

why? if you just use the extensions already in kotlinx.serialization.json

Just bumped into one of the reason. .jsonPrimitive.content will return "null" instead of null if the string is nullable so it needs extra care

[mbonnin]

Same for .jsonObject . If you object is nullable, it'll throw so you'll have to manage that manually at which point might as well write your own extensions