Develop Reference

How to Parse Json in Kotlin Using Retrofit?

i am new to kotlin and i am in learning phase. I have followed many links but didn't able to understand completely.
I want Json response to show in my textview.
Problem: 1
I have tried this code but was unable to get data, but i want to get the items inside data object. Quote and author are coming null.
{
"status": 200,
"message": "Success",
"data": {
"Quote": "The pain you feel today will be the strength you feel tomorrow.",
"Author": ""
},
"time": "0.14 s"
}
Problem: 2
I dont know how to parse this response in textview
object ServiceBuilder {
private val client = OkHttpClient.Builder().build()
private val retrofit = Retrofit.Builder()
.baseUrl("https://url.com.pk/") // change this IP for testing by your actual machine IP
.addConverterFactory(GsonConverterFactory.create())
.client(client)
.build()
fun<T> buildService(service: Class<T>): T{
return retrofit.create(service)
}}
RestApi
interface RestApi{
#Headers("Content-Type: application/json")
#POST("api/getquotes")
abstract fun addUser(#Body userData: UserInfo): Call<UserInfo>}
RestAPiService
class RestApiService
{
fun addUser(userData: UserInfo, onResult: (UserInfo?) -> Unit)
{
val retrofit = ServiceBuilder.buildService(RestApi::class.java)
retrofit.addUser(userData).enqueue(
object : Callback<UserInfo>
{
override fun onFailure(call: Call<UserInfo>, t: Throwable)
{
onResult(null)
}
override fun onResponse( call: Call<UserInfo>, response: Response<UserInfo>)
{
val addedUser = response.body()
Log.d("responsee",""+addedUser)
onResult(addedUser)
}
}
)
}
}
UserInfo
data class UserInfo (
#SerializedName("Quote")
val quote : String,
#SerializedName("Author")
val author : String
)
MainActivity
fun getQuotes() {
val apiService = RestApiService()
val userInfo = UserInfo("","")
apiService.addUser(userInfo) {
Log.d("Error registering user","errter")
/*if ( != null)
{
// it = newly added user parsed as response
// it?.id = newly added user ID
} else {
Log.d("Error registering user","errter")
}*/
}
}
Any help would be appreciated :)

Status, message and data are all part of the response so you need to take care of that. For example this
data class AddUserResponse(
val `data`: UserInfo, //like you defined it
val message: String,
val status: Int,
val time: String
)
This means parameter and response are different so the RestApi needs to be changed to this
abstract fun addUser(#Body userData: UserInfo): Call<AddUserResponse>}
This in turn also change the types in the service like
class RestApiService
{
fun addUser(userData: UserInfo, onResult: (UserInfo?) -> Unit)
{
val retrofit = ServiceBuilder.buildService(RestApi::class.java)
retrofit.addUser(userData).enqueue(
object : Callback<AddUserResponse>
{
override fun onFailure(call: Call<AddUserResponse>, t: Throwable)
{
onResult(null)
}
override fun onResponse( call: Call<AddUserResponse>, response: Response<AddUserResponse>)
{
val addedUser = response.body()
Log.d("responsee",""+addedUser)
onResult(addedUser.data)
}
}
)
}
}
now in getQuotes you will have that it is a UserInfo object
apiService.addUser(userInfo) {
val returnedUserInfo = it
}

just follow my steps :
File->settings->Plugins
search for JSON To Kotlin class and install it
again click on File->New->Kotlin Data class from JSON
paste your json code here and click on generate. It will generate POJO classes and you will good to go.

The first thing I noticed, is that the data in your json is:
"Quote": "The pain you feel today will be the strength you feel tomorrow.",
"Author": ""
While your UserInfo defined #SerializedName("message") for Quote.

how to post with form-data only with retrofit

I try to post data and get the response with POST using retrofit. In postman it works fine but in code it error.
this is the last thing I tried
service
#FormUrlEncoded
#POST("program/get/list-user-program")
fun getProgram(
#Field("comunity") comunity:String,
#Field("programGroupUrl") programGroupUrl:Int
): Call<ListProgramResponse>
activity
val retrofit: Retrofit = Retrofit.Builder()
.baseUrl(URL_BASE)
.addConverterFactory(GsonConverterFactory.create())
.build()
val apiService: Service = retrofit.create(Service::class.java)
val call: Call<ListProgramResponse> = apiService.getProgram("abc", 0)
call.enqueue(object : Callback<ListProgramResponse> {
override fun onResponse(call: Call<ListProgramResponse>, response: Response<ListProgramResponse>) {
Log.e("check", response.body()?.toString())
override fun onFailure(call: Call<ListProgramResponse>, t: Throwable) {
Toast.makeText(applicationContext, "Failure", Toast.LENGTH_SHORT).show()
t.printStackTrace()
}
})
response
data class ProgramBersedekahResponse(
#SerializedName("banner") val banner: String?,
#SerializedName("domainlembaga") val domainlembaga: String?,
#SerializedName("domainprogram") val domainprogram: String?,
#SerializedName("donate") val donatur: Int?
)
but it says java.lang.NumberFormatException: empty String and failure. did anyone know why? please help

Android get data from dynamic url from APi

I found some Api about Pokemon(https://pokeapi.co). And I try get data from this Api and it's work.
The data look like this
But I try to use name of data from Api to get some image with this path "api/v2/pokemon/{name}"
The problem is how can get name out of onResponse or do the other way to get name and image of Pokemon
MainActivity
val retrofit = Retrofit.Builder()
.baseUrl("https://pokeapi.co/")
.addConverterFactory(GsonConverterFactory.create())
.client(HTTPLogger.getLogger())
.build()
val jsonPlaceholderApi = retrofit.create(pokemonService::class.java)
val myCall: Call<PokemonInGen> = jsonPlaceholderApi.getGen(1)
myCall.enqueue(object : Callback<PokemonInGen> {
override fun onResponse(
call: Call<PokemonInGen>,
response: Response<PokemonInGen>
) {
val DataResponse: PokemonInGen = response.body()!!
Timber.i("on do Respon %s", DataResponse)
}
override fun onFailure(call: Call<PokemonInGen>, t: Throwable) {
Timber.i("on do ERROR")
}
})
My Service
interface pokemonService {
#GET("api/v2/generation/{id}")
fun getGen(
#Path("id") id: Int,
): Call<PokemonInGen>
#GET("api/v2/pokemon/{name}")
fun getArtwork(
#Path("name") name: String,
): Call<PokemonArtwork>
}
My Model Data class
data class PokemonInGen(
val pokemon_species: List<PokemonList>)
data class PokemonList(
val name: String,
val url: String,
)

To fetch Pokemon image you should create additional function in your MainActivity class
fun fetchPokemonArtwork(name: String) {
jsonPlaceholderApi.getArtwork(name).enqueue(object : Callback<PokemonArtwork> {
override fun onResponse(
call: Call<PokemonArtwork>,
response: Response<PokemonArtwork>
) {
// An artwork is successful fetched
val artwork = response.body()!!
}
override fun onFailure(call: Call<PokemonArtwork>, t: Throwable) {
// Handle a failure
}
})
}
You should call this function right after you fetched a Pokemon in generation
val myCall: Call<PokemonInGen> = jsonPlaceholderApi.getGen(1)
myCall.enqueue(object : Callback<PokemonInGen> {
override fun onResponse(
call: Call<PokemonInGen>,
response: Response<PokemonInGen>
) {
val DataResponse: PokemonInGen = response.body()!!
Timber.i("on do Respon %s", DataResponse)
// Extract name
val name = DataResponse.pokemon_species.first().name
// Fetch an artwork
fetchPokemonArtwork(name)
}
override fun onFailure(call: Call<PokemonInGen>, t: Throwable) {
Timber.i("on do ERROR")
}
})
P.S. I proceeded from the assumption that you've implemented PokemonArtwork class. Please let me know if you are facing difficulties in comments below.
P.S.S. It's not recommended to make network calls in Activity or Fragment classes. This guide to app architecture should help you to select correct app structure in your future releases.

You can using #Url to support dynamic link in retrofit. Example below:
interface pokemonService {
#GET
Call<PokemonResponse> getListPokemon(#Url String url);
}
And paste your url to browser to see data format.

Get data from nested json using GSON

Can you, please, help me understand how to parse data from nested json file using GSON. I have looked at other similar question posted, but don't see where have i made a mistake. I'm trying to get id, user, technician and an account from my json file.
My JSON file look like this:
{
"operation": {
"result": {
"message": "successful",
"status": "done"
},
"details": [
{
"id": "106818",
"user": "Leona",
"technician": "45441",
"account": "Inc",
"status": "Open"
}
]
}
}
Code:
val url = "https://myURL"
val request = Request.Builder().url(url).build()
val client = OkHttpClient()
client.newCall(request).enqueue(object :Callback{
override fun onFailure(call: Call, e: IOException) {
println("Failed - onFailure")
}
override fun onResponse(call: Call, response: Response) {
val body = response?.body()?.string()
println(body)
val gson = GsonBuilder().create()
gson.fromJson(body, HomeFeed::class.java)
}
})
}
}
class HomeFeed(val details: List<Details>)
class Details(val id: String, val user:String, val technician:String, val account:String)
Error:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.kotlinjsontube, PID: 10905
java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.Collection.size()' on a null object reference
at com.example.kotlinjsontube.MainAdapter.getItemCount(MainAdapter.kt:13)
Thank you.

Your response modeled into a POJO class:
Model.kt
data class Model(
val operation: Operation,
val details: List<Detail>
)
data class Operation(
val result: Result
)
data class Result(
val message: String,
val status: String
)
data class Detail(
val id: String,
val user: String,
val technician: String,
val account: String,
val status: String
)
Class where you make the request:
val url = "https://myURL"
val request = Request.Builder().url(url).build()
val client = OkHttpClient()
client.newCall(request).enqueue(object :Callback{
override fun onFailure(call: Call, e: IOException) {
println("Failed - onFailure")
}
override fun onResponse(call: Call, response: Response) {
val body = response?.body()?.string()
println(body)
val gson = GsonBuilder().create()
gson.fromJson(body, Model::class.java)
}
})

Retrofit - onFailure on non-empty body, onResponse on empty body

My GET request doesn't work properly in Android Studio. I tried to put the same requests in Postman and in result I always got response code 200 with correct body. However, using Retrofit I get onResponse (200 code) when response body is empty (there is no data) and onFailure when response body is not empty (there are some reservations).
EDIT: I have just noticed such error in logs: Expected BEGIN_OBJECT but was STRING at line 1 column 22 path $[0].reservationDate
EDIT2: JSON RESPONSE
[
{
"reservationDate": "2019-10-30",
"id": "4"
}
]
API Service:
#Headers("Authorization: Bearer ...")
#GET("reservations")
fun getSchedule(#Query("id") id: Int,
#Query("reservationDate") reservationDate: LocalDate
): Call<List<ScheduleModel>>
companion object {
fun create(): ScheduleService{
var retrofit = Retrofit.Builder()
.baseUrl("myUrl")
.addConverterFactory(GsonConverterFactory.create())
.build()
return retrofit.create(ScheduleService::class.java)
}
}
}
data class ScheduleModel(
val id: Int,
val reservationDate: LocalDate
)
fun getReservations() {
var service = ScheduleService.create()
var localdate = LocalDate.of(2019,10,30)
var call = service.getSchedule(4, localdate)
call.enqueue(object : Callback<List<ScheduleModel>> {
override fun onResponse(call: Call<List<ScheduleModel>>, response: Response<List<ScheduleModel>>) {
if (response.code() == 200) {
Toast.makeText(applicationContext, "It's ok", Toast.LENGTH_SHORT).show()
}
}
override fun onFailure(call: Call<List<ScheduleModel>>, t: Throwable) {
Toast.makeText(applicationContext, "Failure", Toast.LENGTH_SHORT).show()
}
})
}

Your id and reservationDate in response is a String but you try to parse it as Int and LocalDate. Change the types and it's gonna be work.