How to deserialize raw JSON objects with Moshi/Retrofit

Question

I have a Sticker class and its wrapper:

@JsonClass(generateAdapter = true)
class StickerDto(
        @Json (name = "totalAnimatedStickers") val total: Int,
        @Json(name = "pages") val pages: Int,
        @Json(name = "data") val stickers: List<Sticker>

)

@JsonClass(generateAdapter = true)
class Sticker(
        @Json(name = "name") val name: String,
        @Json(name = "id") val id: String,
        @Json(name = "stickerData") val stickerData: JsonObject,
        var isSelected:Boolean = false
)

The stickerData attribute comes from the api with a dynamic json object with unknown attributes

"stickerData": {}

How do I deserialize an object like that using Moshi?

My current retrofit client:

 private fun createNewFriendsClient(authRefreshClient: AuthRefreshClient,
                                       preferencesInteractor: PreferencesInteractor): FriendsApiClient {

        val logger = run {
            val httpLoggingInterceptor = HttpLoggingInterceptor()
            httpLoggingInterceptor.apply {
                httpLoggingInterceptor.level = if (BuildConfig.DEBUG) HttpLoggingInterceptor.Level.BODY else HttpLoggingInterceptor.Level.NONE
            }
        }

        val okHttp = OkHttpClient.Builder().addInterceptor(logger).authenticator(RefreshUserAuthenticator(authRefreshClient, preferencesInteractor,
                UnauthorizedNavigator(SDKInternal.appContext, Interactors.preferences))).build()


        return Retrofit.Builder()
                .client(okHttp)
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .addConverterFactory(MoshiConverterFactory.create())
                .baseUrl(Interactors.apiEndpoint)
                .build()
                .create(FriendsApiClient::class.java)


    }

Gives me an

"Unable to create converter for class StickerDto"
Caused by NoJsonAdapter for java.util.Comparator<? super java.lang.String>

error. What converter do I need to use if not that Moshi one? Trying to pull it down as a string also gives an error as it is expecting and object. I just need that string.

Edit, the Json string is very long but it begins like this:

{"tileId":"1264373a-24d8-4c10-ae90-d6e8f671410c","friendId":"2c50f187-039a-4f85-b12b-0c802396a611","name":"David Carey","message":"Joined WeAre8","animatedSticker":{"v":"5.5.7","fr":24,"ip":0,"op":48,"w":1024,"h":1024,"nm":"party_popper","ddd":0,"assets":[{"id":"comp_0","layers":[{"ddd":0,"ind":1,"ty":3,"nm":"C | Position","sr":1,"ks":{"o":{"a":0,"k":100,"ix":11},"r":{"a":0,"k":45,"ix":10},"p":{"a":1,"k":[{"i":{"x":0,"y":1},"o":{"x":0.333,"y":0},"t":0,"s":[176,892,0],"to":[-6.667,6.667,0],"ti":[0,0,0]},{"i":{"x":0.833,"y":0.833},"o":{"x":0.333,"y":0},"t":7,"s":[136,932,0],"to":[0,0,0],"ti":[-6.667,6.667,0]},{"t":11,"s":[176,892,0]}],"ix":2},"a":{"a":0,"k":[0,0,0],"ix":1},"s":{"a":1,"k":[{"i":{"x":[0,0,0.667],"y":[1,1,1]},"o":{"x":[0.333,0.333,0.333],"y":[0,0,0]},"t":0,"s":[100,100,100]},{"i":{"x":[0.833,0.833,0.833],"y":[0.833,0.833,1]},"o":{"x":[0.333,0.333,0.333],"y":[0,0,0]},"t":7,"s":[115,75,100]},{"i":{"x":[0,0,0.667],"y":[1,1,1]},"o":{"x":[0.167,0.167,0.167],"y":[0.167,0.167,0]},"t":11,"s":[95,105,100]},{"t":20,"s":[100,100,100]}],"ix":6}},"ao":0,"ef":[{"ty":5,"nm":"Controller","np":13,"mn":"Pseudo/DUIK controller","ix":1,"en":1,"ef":[{"ty":6,"nm":"Icon","mn":"Pseudo/DUIK controller-0001","ix":1,"v":0},{"ty":2,"nm":"Color","mn":"Pseudo/DUIK controller-0002","ix":2,"v":{"a":0,"k":[0.92549020052,0.0941176489,0.0941176489,1],"ix":2}},{"ty":3,"nm":"Position","mn":"Pseudo/DUIK controller-0003","ix":3,"v":{"a":0,"k":[0,0],"ix":3}},{"ty":0,"nm":"Size","mn":"Pseudo/DUIK controller-0004","ix":4,"v":{"a":0,"k":100,"ix":4}},{"ty":0,"nm":"Orientation","mn":"Pseudo/DUIK controller-0005

I think you can write this `val stickerData: JsonObject` as `val stickerData: Map` — denvercoder9, Jul 13 '20 at 12:39
Still getting the error from the question Caused by: java.lang.IllegalArgumentException: Platform class java.util.HashMap in java.util.HashMap requires explicit JsonAdapter to be registered — andrewedgar, Jul 13 '20 at 13:12
I don't understand, if the json has unknown attributes, then how are you gonna use the attributes?! — M D P, Jul 17 '20 at 10:16
The whole string gets used by an animation library. Not sure how the library traverses the string. — andrewedgar, Jul 18 '20 at 03:06
Well for that you only need a simple class for the object that has a single `String` field named `stickerData`. — M D P, Jul 18 '20 at 23:45

score 8 · Accepted Answer · edited Nov 22 '22 at 13:24

Note that JsonObject is a class from the gson package, so if you want to use Moshi you will need to switch to JSONObject which is the default class supported by Android.

To do this you will need to write your own JSONObject adapter.

First, write your adapter class:

import com.squareup.moshi.FromJson
import com.squareup.moshi.JsonReader
import com.squareup.moshi.JsonWriter
import com.squareup.moshi.ToJson
import okio.Buffer
import org.json.JSONException
import org.json.JSONObject

class JSONObjectAdapter {
    
    @FromJson
    fun fromJson(reader: JsonReader): JSONObject? {
        // Here we're expecting the JSON object, it is processed as Map<String, Any> by Moshi
        return (reader.readJsonValue() as? Map<String, Any>)?.let { data ->
            try {
                JSONObject(data)
            } catch (e: JSONException) {
                // Handle exception
                return null
            }
        }
    }
    
    @ToJson
    fun toJson(writer: JsonWriter, value: JSONObject?) {
        if (value != null) {
            writer.value(Buffer().writeUtf8(value.toString()))
        } else {
            writer.value(null as String?)
        }             
    }
   
}

Adjust your retrofit build to provide custom Moshi object when creating the MoshiConverterFactory:

    .addConverterFactory(MoshiConverterFactory.create(Moshi.Builder().add(JSONObjectAdapter()).build()))

and then you are good to go and use JSONObject

@Json(name = "stickerData") val stickerData: JSONObject

Good luck and I hope this helps!

score 2 · Answer 2 · answered Jul 19 '20 at 15:43

Built-in Type Adapters for Moshi include Arrays, Collections, Lists, Sets, and Maps. A JsonObject type is not provided with Moshi itself, but it would be an enhanced Map<String, Any> anyhow, so just use the Map instead of an object.

@JsonClass(generateAdapter = true)
class Sticker(
        @Json(name = "name") val name: String,
        @Json(name = "id") val id: String,
        @Json(name = "stickerData") val stickerData: Map<String, Any>,
        var isSelected: Boolean = false
)

The values are automatically converted as well. Thus you'll find strings, lists or numbers there.

score -2 · Answer 3 · answered Jul 13 '20 at 17:27

-2

I made stickerData into a Map and used a GsonConverterFactory instead of Moshi.

answered Jul 13 '20 at 17:27

andrewedgar

797
1
12
46

1

Still this doesn't give the solution to the question. Its a workaround. What if we need to use the Moshi instead of Gson? – Jaswant Singh Jul 13 '20 at 17:31
1

yep I'd go with gson, I had to do something similar for a very simple object `[ time: '2019-10-11...' , time : 123456 ]` and just gave up and went gson. Moshi is very cumbersome for simple objects that need a simple adapter. – Fabio Jul 17 '20 at 06:59

How to deserialize raw JSON objects with Moshi/Retrofit

3 Answers3