com.google.gson.JsonSyntaxException：java.lang.IllegalStateException：预期 BEGIN_OBJECTRAY BEGIN_OBJECTRAY

Question

I am new to retrofit and I stumbled upon a problem when trying to parse json inside of my application. It looks something like this:

{ "status": "success", "message": "Data selected from database", "data": [ { "id": "4622", "name": "xyz" } ] }

Anyways, its a json inside of json, and my program crashes at this exact line, when I parse just part of the json that isn't nested, it works (status and message part). The app crashes at this exact line: viewModel.getPost()

I have two data classes that I use, one is called Post and in it I hold the values of status and message, and data, but whenever I try to use the Data part of the Post class, the program crashes and I get com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 69 path $.data error. I tried to look online but haven't found any solutions that worked for me in kotlin. Here are my data classes:

data class Post(
val status:String,
val message:String,
val data: Data) 

data class Data (
val id : String ,
val name : String)

Here is my retrofit api:

object RetrofitInstance {

private val retrofit by lazy{
    Retrofit.Builder()
        .baseUrl(BASE_URL)
        .addConverterFactory(GsonConverterFactory.create())
        .build()
}
val api:SimpleApi by lazy{
    retrofit.create(SimpleApi::class.java)
}}

interface SimpleApi {
@GET("token/username")
suspend fun getPost(): Response<Post>}

Post repo:

class Repository {
suspend fun getPost(): Response<Post> {
    return  RetrofitInstance.api.getPost()
}}

And viewModel files I am using:

class MainViewModel(private val repository:Repository): ViewModel() {

val myResponse:MutableLiveData<Response<Post>> = MutableLiveData()

fun getPost(){
    viewModelScope.launch {
        val response=repository.getPost()
        myResponse.value=response
    }
}}

class MainViewModelFactory(private val repository: Repository):ViewModelProvider.Factory {
override fun <T : ViewModel?> create(modelClass: Class<T>): T{
    return MainViewModel(repository) as T
}}

This is the code in which im using the above in the activity:

 val repository=Repository()
    val viewModelFactory=MainViewModelFactory(repository)
    viewModel=ViewModelProvider(this,viewModelFactory).get(MainViewModel::class.java)
    viewModel.getPost()
    viewModel.myResponse.observe(this, Observer { response->
        if(response.isSuccessful && response.body()!=null){
            Log.d("Response", response.body().toString())
            Log.d("Response",response.body()?.message.toString())
            Toast.makeText(this, response.body()?.data!!.id,Toast.LENGTH_LONG).show()
        }
        else{
            Log.d("Error response",response.errorBody().toString())
            Toast.makeText(this,"error",Toast.LENGTH_LONG).show()
        }
        //Toast.makeText(this, response.data.id,Toast.LENGTH_LONG).show()
    })

Any ideas what could I do to get the Data part right so I can work with it in the application? Thank you.

Answer 1

Change type of data in Post Class to List

Answer 2

{ "status": "success", "message": "Data selected from database", "data": [ { "id": "4622", "name": "xyz" } ] }

in this json data is accepting list of object:

data": [ { "id": "4622", "name": "xyz" } ]

but you are having:

data class Post(
val status:String,
val message:String,
val data: Data) 

convert it to:

data class Post(
val status:String,
val message:String,
val data: List<Data)