Kotlin Retrofit Moshi: returns nothing

Question

PROBLEM:

I need to parse the one shown below, JSON, I use Retrofit, Moshi, Kotlin, I use the data class as a placeholder, I output the result to LogCat, but nothing is output.

---

JSON

{
      persons:[
               {
                "name": "Christian",
                "age": 5
               },
               {
                "name": "Marcus",
                "age": 10
               },
               {
                "name": "Norman",
                "age": 20
               }
             ]
}

---

Data Class

data class Persons(
    @Json(name = "name") val name: String,
    @Json(name = "age")  val age: Int
)

---

API Service

private val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()

private val retrofit = Retrofit.Builder()
    .addConverterFactory(MoshiConverterFactory.create(moshi))
    .baseUrl(BASE_URL)
    .build()

interface PersonApiService {
    @GET(ADDITIONAL_URL)
    fun getPersons(): Call<Persons>
}

object PersonApi {
    val retrofitService: PersonApiService by lazy {
        retrofit.create(PersonApiService::class.java)
    }
}

---

Response

override fun onResponse(call: Call<Persons>, response: Response<Persons>) {
         Log.i(TAG, "onResponse: ${response.body()}")                     // RETURNS NOTHING
}

---

Answer 1

Read this article and you will understand everything.

---

A bit of theory:

Remember and learn to distinguish between 2 types of Json: Nested JSON Object | Array of JSON Objects

Nested JSON Objecs:                      | Array of JSON Objects
                                         |          
       {                                 |          
         persons:[                       |          [  
                  {                      |           {
                    "name": "Christian", |             "name": "Christian",
                    "age": 5             |             "age": 5       
                  },                     |           },     
                  {                      |           {  
                    "name": "Marcus",    |             "name": "Marcus",
                    "age": 10            |             "age": 10
                  },                     |           }, 
                  {                      |           { 
                    "name": "Norman",    |             "name": "Norman",
                    "age": 20            |             "age": 20   
                  }                      |           }
                 ]                       |          ]
       }  

Your implementation would fit if your JSON was in (Array of JSON Objects) format|

---

Data Class for Nested JSON Object

data class Persons(
    @Json(name = "persons") val persons: List<PersonProperty>
)

data class PersonProperty(
    @Json(name = "name") val name: String,
    @Json(name = "age")  val age: Int
)

Response

override fun onResponse(call: Call<Persons>, response: Response<Persons>) {
         Log.i(TAG, "onResponse: ${response.body()}")                     // RETURNS List Persons
}