How to deserialize string for unity JsonUtility.fromJson() method, properly

Question

Ok so basically I am trying to get the hang of de-serializing and serializing custom classes in C# (unity) from strings. Json seemed to be the obvious method and is usable with mysql which I plan to use to store player data.

I can't get past a test string example I am trying to run to make a "Dummy" playerdata object. From there I will pass the player object to an Initialize method on the player at login.

Again I am just trying to use a (dummy) string (Which is the results of mysql queries right?) to generate a player data object. This is what I have.

PlayerData.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class PlayerData
{
    public string Name {get; protected set;}
    public uint Attack {get; protected set;}
    public uint Defense {get; protected set;}
    public uint Armor {get; protected set;}
    public uint MovementSpeed {get; protected set;}
    public uint MagicLevel {get; protected set;}

    public static PlayerData Serialize(string obj)
    {
      return JsonUtility.FromJson<PlayerData>(obj);
    }
}

the code I use to run it is this:

String test = @"{
    ""Name"": ""Chase"",
    ""Attack"" : 50,
    ""Defense"" : 35,
    ""Armor"" : 12,
    ""MovementSpeed"" : 60,
    ""MagicLevel"" : 15,
}";
PlayerData data = PlayerData.Serialize(test);
Debug.Log(data.Attack);

The error I get is this.

ArgumentException: JSON parse error: Missing a name for object member.

I really need help here, I have tried to ecapsulate the int variables with the double quotation marks, tried to do the same with all values, hell I have tried it so many ways, each time either that error or invalid value. Please any help would be much appreciated.

Answer 1

You have two issues. The first one is Unity does not like your trailing comma after MagicLevel. Remove that:

String test = @"{
    ""Name"": ""Chase"",
    ""Attack"" : 50,
    ""Defense"" : 35,
    ""Armor"" : 12,
    ""MovementSpeed"" : 60,
    ""MagicLevel"" : 15
}";

Second you are having issues because your properties have a protected set. This means Unity can never assign those values because JsonUtility.FromJson() is not your PlayerData class or a class that inherits from it so it does not have the access to set those properties.

I understand that you want to keep these properties from being set by anything other than the serialization (or later a constructor). To do that in unity specifically, you need the [SerializeField] attribute:

[System.Serializable]
public class PlayerData
{
    [SerializeField]
    protected string _name 
    
    public string Name {get { return _name;}}

    [SerializeField]
    protected uint _attack;
    
    public uint Attack {get { return _attack;}}

    [SerializeField]
    protected uint _defense;
    
    public uint Defense {get { return _defense;}}

    [SerializeField]
    protected uint _armor;
    
    public uint Armor {get { return _armor;}}

    [SerializeField]
    protected uint _movementSpeed;
    
    public uint MovementSpeed {get { return _movementSpeed;}}

    [SerializeField]
    protected uint _magicLevel;
    
    public uint MagicLevel {get { return _magicLevel;}}

    public static PlayerData Deserialize(string obj)
    {
        return JsonUtility.FromJson<PlayerData>(obj);
    }
}

I went and renamed your Serialize() method to Deserialize() because that's what its actually doing.

Edit

Based on your trial and error it seems that Unity takes issue with serializing properties. Which is unfortunate because properties are the prefered way to handle setting and getting of data in an object. I have edited my example code to reflect protected fields with public properties