Retrofit respone null in Data Class - kotlin

Question

I'm a newbie about Kotlin. My first project is to consume a rest api. I already made that using retrofit. But I have a problem when I'm logging the response, my data class is null. I don't know where is the error.
My Rerofit Client
object RetrofitClient {
var retrofit: Retrofit? = null
fun getClient(baseUrl: String): Retrofit? {
if (retrofit == null) {
//TODO While release in Google Play Change the Level to NONE
val interceptor = HttpLoggingInterceptor()
interceptor.level = HttpLoggingInterceptor.Level.BODY
val client = OkHttpClient.Builder()
.addInterceptor(interceptor)
.connectTimeout(100, TimeUnit.SECONDS)
.readTimeout(100, TimeUnit.SECONDS)
.build()
retrofit = Retrofit.Builder()
.client(client)
.baseUrl(baseUrl)
.addConverterFactory(GsonConverterFactory.create())
.build()
}
return retrofit
}
}
My Interface
public interface ApiLoginService {
#POST("UserManagementCoreAPI/api/v1/users")
fun loginService(#Body request: RequestBody): Call<DataLogin>
}
object ApiUtils {
val BASE_URL = "------"
val apiLoginService: ApiLoginService
get() = RetrofitClient.getClient(BASE_URL)!!.create(ApiLoginService::class.java)
}
My class data
data class DataLogin (
#SerializedName("employeeId") val employeeId : String,
#SerializedName("fullName") val fullName : String,
#SerializedName("loginConfins") val loginConfins : String,
#SerializedName("branchId") val branchId : String,
#SerializedName("isActive") val isActive : String
)
Main Activity
mApiLoginService!!.loginService(requestBody).enqueue(object : Callback<DataLogin>{
override fun onResponse(call: Call<DataLogin>, response: Response<DataLogin>) {
if(response.isSuccessful()){
if(response.body().toString() == null){
Log.d(tag,"Null")
}else{
Log.d(tag,"Logging In " + response.body()!!)
progressBar.visibility = View.GONE
btn_submit.visibility = View.VISIBLE
startActivity(Intent(this#MainActivity, HomeActivity::class.java))
}
}else{
Toast.makeText(applicationContext, "Invalid username or password", Toast.LENGTH_LONG).show()
Log.d(tag,"Error " + response.errorBody().toString())
progressBar.visibility = View.GONE
btn_submit.visibility = View.VISIBLE
}
}
override fun onFailure(call: Call<DataLogin>, t: Throwable) {
progressBar.visibility = View.GONE
btn_submit.visibility = View.VISIBLE
}
})
My Respone Log
message: Logging In DataLogin(employeeId=null, fullName=null, loginConfins=null, branchId=null, isActive=null)
I don't know where is the error and why my data is null. If the response succeeds is still gives me null.
This is a postman example

Answer 1

You have an issue with your schema , Your DataLogin class is different of your postman schema , Retrofit is waiting for : fullName, isActive ...., and the response is : header , data .. , you have to create class that contains header as variable of type Header(errors:List<AnotherClass>), data as variable of type Data(data(List<DataLogin>),totalRecord:Int), i would suggest if you use helper website like JSON to Class , parse your postman response there , and he will give you your correct response class but it's will be in java , you have to rewrite the code yourself of just copy paste in android studio and he will convert the code to Kotlin for you. (in the web site , check Source type: JSON)

Answer 2

You have to match the json structure with your data classes if you do not provide a custom adapter to Gson. So if you want to have a result, maybe something like this will work:
data class Response(
#SerializedName("headers") val headers: List<Any>,
#SerializedName("data") val data: Data
)
data class Data(
#SerializedName("data") val data: List<DataLogin>,
#SerializedName("totalRecord") val totalRecord: Int
)
data class DataLogin (
#SerializedName("employeeId") val employeeId : String,
#SerializedName("fullName") val fullName : String,
#SerializedName("loginConfins") val loginConfins : String,
#SerializedName("branchId") val branchId : String,
#SerializedName("isActive") val isActive : String
)
You need to return a Response object from your retrofit call.
Also a few tips about kotlin, Gson works well for Java, but it has some issues with kotlin (about null safety). I use Moshi when the project language is kotlin and it works well with it.
Try to avoid using !! in kotlin because it will cause RuntimeException. There are other ways of checking null and to protect your code from RuntimeExceptions.