Question

I’m working with JsonFx using C# (via Mono in Unity3D) to serialize some data but I get: “JsonTypeCoercionException: Only objects with default constructors can be deserialized. (Level[])” when I try to deserialize the data.

I’ve tried adding a default constructor to the serialized class but I still get the error. Fwiw, I tried the different suggestions in a similar thread:
http://forum.unity3d.com/threads/117256-C-deserialize-JSON-array

Here’s my code:

//C#
using System;
using UnityEngine;
using System.Collections;
using JsonFx.Json;
using System.IO;

public class LoadLevel : MonoBehaviour {


string _levelFile = "levels.json"; 
Level[] _levels; 

void Start () {

    if (!File.Exists (_levelFile)){

        // write an example entry so we have somethng to read
        StreamWriter sw = File.CreateText(_levelFile);

        Level firstLevel = new Level();
        firstLevel.LevelName = "First Level";               
        firstLevel.Id = Guid.NewGuid().ToString();


        sw.Write(JsonFx.Json.JsonWriter.Serialize(firstLevel)); 
        sw.Close();

    }


    // Load our levels
    if(File.Exists(_levelFile)){

        StreamReader sr = File.OpenText(_levelFile);

        _levels = JsonReader.Deserialize<Level[]>(sr.ReadToEnd());

    }

}
}

And here’s the object it’s serializing:

using UnityEngine;
using System.Collections;
using System; 

public class Level {

public string Id;
public string LevelName;

public Level() {}

}

Any ideas? I’ve tried both with and without the Level() constructor.

Answer 1

I believe your JSON stream actually needs to contain an array for this to work – it can’t just be a single element since you’re asking for an array in Deserialize.