java.lang.IllegalStateException：预期为 BEGIN_ARRAY，但在第 1 行第 1 列路径 $ 错误处为 STRING

Question

I know there are some other topics on this problem but I couldn't find the solution for my error so if you have any suggestions, please let me know. I'm trying to create a POST request with a param in the body to retrieve some data from the API.

My DataApi interface:

interface ChartsDataApi {

@POST(NetworkUtils.CASH_COLLECTION_URL)
fun getCashCollection(@Body guid: String) : Call<List<CashCollection>>

@POST(NetworkUtils.TICKETS_DETAILS_URL)
fun getTicketsDetails() : Call<List<TicketDetails>>

}

My fun where I'm using Retrofit and where I'm trying to get the response:

private fun geCashCollectionDetails(){
    var params : MutableMap<String, String> = HashMap()
    val BASE_URL = " here i wrote the base URL "
    val gson = GsonBuilder()
            .setLenient()
            .create()
   val api = Retrofit.Builder()
           .baseUrl(BASE_URL)
           .addConverterFactory(GsonConverterFactory.create(gson))
           .build()
           .create(ChartsDataApi::class.java)

    GlobalScope.launch(Dispatchers.IO){
        val response = api.getCashCollection(" **here i wrote the guid** ").awaitResponse()
        if(response.isSuccessful){
            val day = response.body()!!.lastIndex
            Log.d("RAZZ", day.toString())
            withContext(Dispatchers.Main){
            }
        }
    }

My Data Class for CashCollection:

data class CashCollection(
    @SerializedName("label")
    val label: String?,
    @SerializedName("value")
    val value: String?)

Response from the server: {"data":[{"label":"12.10.2020","value":"0,00"},{"label":"16.10.2020","value":"0,00"},{"label":"17.10.2020","value":"0,00"},{"label":"18.10.2020","value":"0,00"}],"currency":"EUR"}

Process: com.eschbachit.citylinemobile, PID: 32529
com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:226)
    at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:37)
    at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:25)
    at retrofit2.OkHttpCall.parseResponse(OkHttpCall.java:243)
    at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:153)
    at okhttp3.RealCall$AsyncCall.execute(RealCall.java:174)
    at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
    at java.lang.Thread.run(Thread.java:776)
 Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 1 path $
    at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:385)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:215)
    at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:37) 
    at retrofit2.converter.gson.GsonResponseBodyConverter.convert(GsonResponseBodyConverter.java:25) 
    at retrofit2.OkHttpCall.parseResponse(OkHttpCall.java:243) 
    at retrofit2.OkHttpCall$1.onResponse(OkHttpCall.java:153) 
    at okhttp3.RealCall$AsyncCall.execute(RealCall.java:174) 
    at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607) 
    at java.lang.Thread.run(Thread.java:776) 

When I'm trying to test and check the data I'm receiving, I get that error.

Answer 1

Please provide your data classes and response from server. This error means data from server can't be mapped into data classes that you provide as result of those requests.

Ok, data class must exactly reflect the structure of the response. Your CashCollection class must be

data class CashCollection(
    val data: ArrayList<CashCollectionItem>,
    val currency: String
) {
   data class CashCollectionItem(
       @SerializedName("label")
       val label: String?,
       @SerializedName("value")
       val value: String?)
}

and type of response Call<CashCollection>

Answer 2

It appears you have incorrectly mapped your api response to kotlin classes. In your Retrofit api you say you expect the api to return a list of CashCollections ( [{"label":"12.12.1212", "value": ""0,00}] ), but the server returns a json object where that array is in the data property: {"data":[{"label":"12.12.1212", "value": "0,00"}]}

You should update your retrofit interface to correspond to what the api returns:

class CashCollectionResponse(
  @SerializedName("data") data: List<CashCollection>
)

interface ChartsDataApi {
  @POST("GetTheData")
  fun getCashCollection(@Body guid: String): Call<CashCollectionResponse>
}