Parse JSON object string from json value

Question

I'm making a request to a request to an API and the response is a JSON object, this json object contains a string that is another json object. I'm trying to use kotlinx.serialization to handle the deserialization of this object.

I could override the deserialize functionality myself but that kind of defeats the point of using this library

I hoped something like this would have worked.

@Serializable
data class Foo(val data: Data)

@Serializable
data class Data(val foo: String)

For something like the following Object

{
  "data":"{\"foo\":\"bar\"}"
}

I expect to get an Object Foo with property data = Object Data with property foo = "bar"

However I get the following error

java.lang.IllegalStateException: Expected class kotlinx.serialization.json.JsonArray (Kotlin reflection is not available) but found class kotlinx.serialization.json.JsonLiteral (Kotlin reflection is not available)

Hi, @spoderbiggen you want this JSON as your model(pojo) class right? — Happy Singh, Jul 18 '19 at 17:52
@HappySingh yes I'm sorry if I didn't make this clear in my question — Spiderbiggen, Jul 18 '19 at 18:42
Possible duplicate of [Cannot convert JSON data properly](https://stackoverflow.com/questions/57114952/cannot-convert-json-data-properly) — Alireza Tizfahm Fard, Jul 21 '19 at 04:36

score 0 · Answer 1 · answered Aug 20 '19 at 14:09

You did not specify how you are doing the deserialization. To get what you expect there you would have to specify the correct serializer.

val expectedFoo = Json.parse(Foo.serializer(), """{"data":{"foo":"bar"}}""")

Note In my answer I'm assuming you meant to use a slightly different example string.

In your example json string, the data key corresponds to a String value, not to an object. Please see the difference between the following:

{
  "data":"{\"foo\":\"bar\"}"
}

{
  "data": { "foo": "bar" }
}

So, in any situation, to parse that original example you would need to use some intermediate representation and parse the string representation in between.

@Serializable
data class Intermediate(val data: String)
//...
val intermediateFoo = Json.parse(Intermediate.serializer(), """{"data":"{\"foo\":\"bar\"}"}""")
val expectedFoo = Foo(data = Json.parse(Data.serializer(), intermediateFoo.data))

Parse JSON object string from json value

1 Answers1