I am trying to use Ktor and Kotlinx Serialization to pull some dummy post data form jsonplaceholder.typicode.com (here) and deserialize the array. However, I get the following error:
Error:Expected class kotlinx.serialization.json.JsonObject (Kotlin reflection is not available) as the serialized body of kotlinx.serialization.Polymorphic<List>, but had class kotlinx.serialization.json.JsonArray (Kotlin reflection is not available)
Where in my code am I specifying that I am expecting the data as JsonObjects and not JsonArrays? This is likely the error, but I don't see where in the code I specify this.
Thanks in advance for the help.
Relevant code is posted here:
LoginRegisterFragment.kt
package com.example.groupupandroid
import android.content.Intent
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.lifecycle.lifecycleScope
import androidx.navigation.Navigation
import androidx.navigation.fragment.findNavController
import com.example.groupupandroid.databinding.ActivityMainBinding
import com.example.groupupandroid.databinding.FragmentLoginRegisterBinding
import data.remote.PostResponse
import data.remote.PostsService
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.launch
class LoginRegisterFragment : Fragment(){
// Getting xml objects
private var binding: FragmentLoginRegisterBinding? = null
// Creating service for networking
private lateinit var service: PostsService
private var posts: List<PostResponse> = emptyList()
//@Composable
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentLoginRegisterBinding.inflate(layoutInflater)
lifecycleScope.launch {getPosts()}
// Inflate the layout for this fragment
return binding?.root
}
private suspend fun getPosts() {
service = PostsService.create()
posts = service.getPosts()
print(posts)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
// If register button is tapped make register visible
binding?.registerToggleButton?.setOnClickListener {
binding?.registerFields?.visibility = View.VISIBLE
binding?.loginFields?.visibility = View.GONE
}
// If login button is tapped make login visible
binding?.loginToggleButton?.setOnClickListener {
binding?.registerFields?.visibility = View.GONE
binding?.loginFields?.visibility = View.VISIBLE
}
// If login button is pushed swap to maps
binding?.loginButton?.setOnClickListener {
findNavController().navigate(R.id.loginToHomeScreen)
}
// If register button is pushed swap to maps
binding?.registerButton?.setOnClickListener {
findNavController().navigate(R.id.loginToHomeScreen)
}
binding?.materialButtonToggleGroup?.check(binding?.loginToggleButton!!.id)
}
override fun onDestroyView() {
super.onDestroyView()
binding = null
}
}
PostResponse.kt
package data.remote
import kotlinx.serialization.Serializable
@Serializable
data class PostResponse (
val body: String,
val title: String,
val id: Int,
val userId: Int
)
PostsServiceImplementation.kt
package data.remote
import io.ktor.client.*
import io.ktor.client.call.*
import io.ktor.client.request.*
import io.ktor.client.statement.*
import io.ktor.http.*
import io.ktor.util.*
import java.lang.Exception
class PostsServiceImplementation(private val client: HttpClient): PostsService
{
override suspend fun getPosts(): List<PostResponse> {
return try {
client.get {url(HttpRoutes.POSTS)}.body()
} catch(e: Exception){
println("Error:${e.message}")
emptyList()
}
}
override suspend fun createPosts(postRequest: PostRequest): PostResponse? {
return try {
client.post {
url(HttpRoutes.POSTS)
contentType(ContentType.Application.Json)
setBody(postRequest)
}.body()
} catch(e: Exception) {
println("Error:${e.message}")
null
}
}
}
Edit: More relevant code.
HttpRoutes.kt
package data.remote
object HttpRoutes {
private const val BASE_URL = "https://jsonplaceholder.typicode.com"
const val POSTS = "$BASE_URL/posts"
}
PostsService.kt
package data.remote
import io.ktor.client.*
import io.ktor.client.engine.android.*
import io.ktor.client.plugins.contentnegotiation.*
import io.ktor.client.plugins.kotlinx.serializer.*
import io.ktor.client.plugins.logging.*
import io.ktor.client.statement.*
import io.ktor.serialization.kotlinx.json.*
interface PostsService {
suspend fun getPosts(): List<PostResponse>
suspend fun createPosts(postRequest: PostRequest): PostResponse?
companion object {
fun create():PostsService {
return PostsServiceImplementation (
client = HttpClient(Android) {
install(Logging) {
level = LogLevel.ALL
}
install(ContentNegotiation) {
json()
}
}
)
}
}
}
PostRequest.kt
package data.remote
import kotlinx.serialization.Serializable
@Serializable
data class PostRequest (
val body: String,
val title: String,
val userId: Int
)
