GSON deserialization of a wrapped list of objects

Question

I am trying to de-serialize a list of objects from a JSON response. The JSON array has a key, which is causing issues with using GSON to de-serialize it.

I have about 20 objects similar to this.

public class Device extends Entity {
  String device_id;
  String device_type;
  String device_push_id;
}

For most there is an API method which returns a list of objects. The returned JSON looks like this. Because of other clients, changing the format of the JSON is not a reasonable option at this point.

{
   "devices":[
      {
         "id":"Y3mK5Kvy",
         "device_id":"did_e3be5",
         "device_type":"ios"
      },
      {
         "id":"6ZvpDPvX",
         "device_id":"did_84fdd",
         "device_type":"android"
      }
   ]
}

In order to parse this type of response I'm currently using a mix of org.json methods and Gson.

JSONArray jsonResponse = new JSONObject(response).getJSONArray("devices");

Type deviceListType = new TypeToken<List<Device>>() {}.getType();
ArrayList<Device> devices = gson.fromJson(jsonResponse.toString(), deviceListType);

I'm looking for a cleaner method of doing the deserialization as I'd like to use Retrofit. The answer in Get nested JSON object with GSON using retrofit is close to what I need, but doesn't handle Lists. I've copied the generic version of the answer here:

public class RestDeserializer<T> implements JsonDeserializer<T> {
  private Class<T> mClass;
  private String mKey;

  public RestDeserializer(Class<T> targetClass, String key) {
    mClass = targetClass;
    mKey = key;
  }

  @Override
  public T deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext)
    throws JsonParseException {

    JsonElement value = jsonElement.getAsJsonObject().get(mKey);
    if (value != null) {
      return new Gson().fromJson(value, mClass);
    } else {
      return new Gson().fromJson(jsonElement, mClass);
    }
  }
}

My goal is to have this call "just work".

@GET("/api/v1/protected/devices")
public void getDevices(Callback<List<Device>> callback);

Answer 1

Use the below class

public class Devices {

@Expose
private List<Device> devices = new ArrayList<Device>();

/**
* 
* @return
* The devices
*/
public List<Device> getDevices() {
return devices;
}

/**
* 
* @param devices
* The devices
*/
public void setDevices(List<Device> devices) {
this.devices = devices;
}

}

Device class

public class Device extends Entity {
  @Expose
  String id;
   @Expose
  String device_id;
  @Expose
  String device_type;
}

or

public class Device extends Entity {
  @Expose @SerializedName("id")
  String deviceId;
   @Expose @SerializedName("device_id")
  String devicePushId;
  @Expose @SerializedName("device_type")
  String deviceType;
}

update retrofit method to

@GET("/api/v1/protected/devices")
public void getDevices(Callback<Devices> callback);

devices.getDevices() //call inside callback method will give you the list

Also, you wont require the custom deserializer