[FIXED] How to get the first data object of a data object (REST api)

Issue

I Have a REST api that contains the data like this way

{
   ...
   ... //<- more data here
   ...

   "currencies": {
       "BTN": {
          "name": "Bhutanese ngultrum",
          "symbol": "Nu."
       },
       "INR": {
          "name": "Indian rupee",
          "symbol": "₹"
       }
   }

  ...
  ... //<- more data here
  ...
}

i am doing a project in java where i need to use okhttp and show information about a country from an available rest api and before when i used this api it had all the data in currencies in an data array and that was helpful as you can just get the first zero object from the array , but after they updated the api they made all data in currencies an object and i only want the first object , any way i can get it?

Solution

OK, so you have two options here ...

Option 1. Create two classes like this and use ObjectMapper class to do automatic deserealisation for you.

class CurrencyData {
  String name;
  String symbol;
}

class CurrencyJsonResponse {
   CurrencyData INR;
   CurrencyData BTN;
}

public static void main(String[] args) {
   OkHttpClient client = // build an instance;
   ObjectMapper objectMapper = new ObjectMapper(); 
   ResponseBody responseBody = client.newCall(request).execute().body(); 
   CurrencyJsonResponse currencyResponse = objectMapper.readValue(responseBody.string(), CurrencyJsonResponse.class);
   //Get data by using getters on currencyResponse object
}

Option 2 You can write a custom deserealizer by extending the StdDeserializer<T> class. You'll have to programmatically inspect the JsonNode parse tree and assemble the object that you want.

This article explains how to do it and comes with a working code sample

Answered By - Arthur Klezovich