Serialize and Deserialize Json and Json Array in Unity

Question

I have a list of items send from a PHP file to unity using WWW.

The WWW.text looks like:

[
    {
        "playerId": "1",
        "playerLoc": "Powai"
    },
    {
        "playerId": "2",
        "playerLoc": "Andheri"
    },
    {
        "playerId": "3",
        "playerLoc": "Churchgate"
    }
]

Where I trim the extra [] from the string. When I try to parse it using Boomlagoon.JSON, only the first object is retrieved. I found out that I have to deserialize() the list and have imported MiniJSON.

But I am confused how to deserialize() this list. I want to loop through every JSON object and retrieve data. How can I do this in Unity using C#?

The class I am using is

public class player
{
    public string playerId { get; set; }
    public string playerLoc { get; set; }
    public string playerNick { get; set; }
}

After trimming the [] I am able to parse the json using MiniJSON. But it is returning only the first KeyValuePair.

IDictionary<string, object> players = Json.Deserialize(serviceData) as IDictionary<string, object>;

foreach (KeyValuePair<string, object> kvp in players)
{
    Debug.Log(string.Format("Key = {0}, Value = {1}", kvp.Key, kvp.Value));
}

Thanks!

Answer 1

Unity added JsonUtility to their API after 5.3.3 Update. Forget about all the 3rd party libraries unless you are doing something more complicated. JsonUtility is faster than other Json libraries. Update to Unity 5.3.3 version or above then try the solution below.

JsonUtility is a lightweight API. Only simple types are supported. It does not support collections such as Dictionary. One exception is List. It supports List and List array!

If you need to serialize a Dictionary or do something other than simply serializing and deserializing simple datatypes, use a third-party API. Otherwise, continue reading.

Example class to serialize:

[Serializable]
public class Player
{
    public string playerId;
    public string playerLoc;
    public string playerNick;
}

1. ONE DATA OBJECT (NON-ARRAY JSON)

Serializing Part A:

Serialize to Json with the public static string ToJson(object obj); method.

Player playerInstance = new Player();
playerInstance.playerId = "8484239823";
playerInstance.playerLoc = "Powai";
playerInstance.playerNick = "Random Nick";

//Convert to JSON
string playerToJson = JsonUtility.ToJson(playerInstance);
Debug.Log(playerToJson);

Output:

{"playerId":"8484239823","playerLoc":"Powai","playerNick":"Random Nick"}

---

Serializing Part B:

Serialize to Json with the public static string ToJson(object obj, bool prettyPrint); method overload. Simply passing true to the JsonUtility.ToJson function will format the data. Compare the output below to the output above.

Player playerInstance = new Player();
playerInstance.playerId = "8484239823";
playerInstance.playerLoc = "Powai";
playerInstance.playerNick = "Random Nick";

//Convert to JSON
string playerToJson = JsonUtility.ToJson(playerInstance, true);
Debug.Log(playerToJson);

Output:

{
    "playerId": "8484239823",
    "playerLoc": "Powai",
    "playerNick": "Random Nick"
}

---

Deserializing Part A:

Deserialize json with the public static T FromJson(string json); method overload.

string jsonString = "{\"playerId\":\"8484239823\",\"playerLoc\":\"Powai\",\"playerNick\":\"Random Nick\"}";
Player player = JsonUtility.FromJson<Player>(jsonString);
Debug.Log(player.playerLoc);

Deserializing Part B:

Deserialize json with the public static object FromJson(string json, Type type); method overload.

string jsonString = "{\"playerId\":\"8484239823\",\"playerLoc\":\"Powai\",\"playerNick\":\"Random Nick\"}";
Player player = (Player)JsonUtility.FromJson(jsonString, typeof(Player));
Debug.Log(player.playerLoc);

---

Deserializing Part C:

Deserialize json with the public static void FromJsonOverwrite(string json, object objectToOverwrite); method. When JsonUtility.FromJsonOverwrite is used, no new instance of that Object you are deserializing to will be created. It will simply re-use the instance you pass in and overwrite its values.

This is efficient and should be used if possible.

Player playerInstance;
void Start()
{
    //Must create instance once
    playerInstance = new Player();
    deserialize();
}

void deserialize()
{
    string jsonString = "{\"playerId\":\"8484239823\",\"playerLoc\":\"Powai\",\"playerNick\":\"Random Nick\"}";

    //Overwrite the values in the existing class instance "playerInstance". Less memory Allocation
    JsonUtility.FromJsonOverwrite(jsonString, playerInstance);
    Debug.Log(playerInstance.playerLoc);
}

---

2. MULTIPLE DATA(ARRAY JSON)

Your Json contains multiple data objects. For example playerId appeared more than once. Unity's JsonUtility does not support array as it is still new but you can use a helper class from this person to get array working with JsonUtility.

Create a class called JsonHelper. Copy the JsonHelper directly from below.

public static class JsonHelper
{
    public static T[] FromJson<T>(string json)
    {
        Wrapper<T> wrapper = JsonUtility.FromJson<Wrapper<T>>(json);
        return wrapper.Items;
    }

    public static string ToJson<T>(T[] array)
    {
        Wrapper<T> wrapper = new Wrapper<T>();
        wrapper.Items = array;
        return JsonUtility.ToJson(wrapper);
    }

    public static string ToJson<T>(T[] array, bool prettyPrint)
    {
        Wrapper<T> wrapper = new Wrapper<T>();
        wrapper.Items = array;
        return JsonUtility.ToJson(wrapper, prettyPrint);
    }

    [Serializable]
    private class Wrapper<T>
    {
        public T[] Items;
    }
}

Serializing Json Array:

Player[] playerInstance = new Player[2];

playerInstance[0] = new Player();
playerInstance[0].playerId = "8484239823";
playerInstance[0].playerLoc = "Powai";
playerInstance[0].playerNick = "Random Nick";

playerInstance[1] = new Player();
playerInstance[1].playerId = "512343283";
playerInstance[1].playerLoc = "User2";
playerInstance[1].playerNick = "Rand Nick 2";

//Convert to JSON
string playerToJson = JsonHelper.ToJson(playerInstance, true);
Debug.Log(playerToJson);

Output:

{
    "Items": [
        {
            "playerId": "8484239823",
            "playerLoc": "Powai",
            "playerNick": "Random Nick"
        },
        {
            "playerId": "512343283",
            "playerLoc": "User2",
            "playerNick": "Rand Nick 2"
        }
    ]
}

---

Deserializing Json Array:

string jsonString = "{\r\n    \"Items\": [\r\n        {\r\n            \"playerId\": \"8484239823\",\r\n            \"playerLoc\": \"Powai\",\r\n            \"playerNick\": \"Random Nick\"\r\n        },\r\n        {\r\n            \"playerId\": \"512343283\",\r\n            \"playerLoc\": \"User2\",\r\n            \"playerNick\": \"Rand Nick 2\"\r\n        }\r\n    ]\r\n}";

Player[] player = JsonHelper.FromJson<Player>(jsonString);
Debug.Log(player[0].playerLoc);
Debug.Log(player[1].playerLoc);

Output:

Powai

User2

---

If this is a Json array from the server and you did not create it by hand:

You may have to Add {"Items": in front of the received string then add } at the end of it.

I made a simple function for this:

string fixJson(string value)
{
    value = "{\"Items\":" + value + "}";
    return value;
}

then you can use it:

string jsonString = fixJson(yourJsonFromServer);
Player[] player = JsonHelper.FromJson<Player>(jsonString);

---

3.Deserialize json string without class && De-serializing Json with numeric properties

This is a Json that starts with a number or numeric properties.

For example:

{ 
"USD" : {"15m" : 1740.01, "last" : 1740.01, "buy" : 1740.01, "sell" : 1744.74, "symbol" : "$"}, 

"ISK" : {"15m" : 179479.11, "last" : 179479.11, "buy" : 179479.11, "sell" : 179967, "symbol" : "kr"},

"NZD" : {"15m" : 2522.84, "last" : 2522.84, "buy" : 2522.84, "sell" : 2529.69, "symbol" : "$"}
}

Unity's JsonUtility does not support this because the "15m" property starts with a number. A class variable cannot start with an integer.

Download SimpleJSON.cs from Unity's wiki.

To get the "15m" property of USD:

var N = JSON.Parse(yourJsonString);
string price = N["USD"]["15m"].Value;
Debug.Log(price);

To get the "15m" property of ISK:

var N = JSON.Parse(yourJsonString);
string price = N["ISK"]["15m"].Value;
Debug.Log(price);

To get the "15m" property of NZD:

var N = JSON.Parse(yourJsonString);
string price = N["NZD"]["15m"].Value;
Debug.Log(price);

The rest of the Json properties that doesn't start with a numeric digit can be handled by Unity's JsonUtility.

---

4.TROUBLESHOOTING JsonUtility:

Problems when serializing with JsonUtility.ToJson?

Getting empty string or "{}" with JsonUtility.ToJson?

A. Make sure that the class is not an array. If it is, use the helper class above with JsonHelper.ToJson instead of JsonUtility.ToJson.

B. Add [Serializable] to the top of the class you are serializing.

C. Remove property from the class. For example, in the variable, public string playerId { get; set; } remove { get; set; }. Unity cannot serialize this.

Problems when deserializing with JsonUtility.FromJson?

A. If you get Null, make sure that the Json is not a Json array. If it is, use the helper class above with JsonHelper.FromJson instead of JsonUtility.FromJson.

B. If you get NullReferenceException while deserializing, add [Serializable] to the top of the class.

C.Any other problems, verify that your json is valid. Go to this site here and paste the json. It should show you if the json is valid. It should also generate the proper class with the Json. Just make sure to remove remove { get; set; } from each variable and also add [Serializable] to the top of each class generated.

---

Newtonsoft.Json:

If for some reason Newtonsoft.Json must be used then as of February 2022 it may now be obtained directly from Unity from here: com.unity.nuget.newtonsoft-json@3.0. Just add com.unity.nuget.newtonsoft-json via the package manager. For details see Install official via UPM by kalle (jag).

You can also check out the forked version for Unity from SaladLab / Json.Net.Unity3D. Note that you may experience crash if certain feature is used. Be careful.

---

To answer your question:

Your original data is

 [{"playerId":"1","playerLoc":"Powai"},{"playerId":"2","playerLoc":"Andheri"},{"playerId":"3","playerLoc":"Churchgate"}]

Add {"Items": in front of it then add } at the end of it.

Code to do this:

serviceData = "{\"Items\":" + serviceData + "}";

Now you have:

 {"Items":[{"playerId":"1","playerLoc":"Powai"},{"playerId":"2","playerLoc":"Andheri"},{"playerId":"3","playerLoc":"Churchgate"}]}

To serialize the multiple data from php as arrays, you can now do

public player[] playerInstance;
playerInstance = JsonHelper.FromJson<player>(serviceData);

playerInstance[0] is your first data

playerInstance[1] is your second data

playerInstance[2] is your third data

or data inside the class with playerInstance[0].playerLoc, playerInstance[1].playerLoc, playerInstance[2].playerLoc ......

You can use playerInstance.Length to check the length before accessing it.

NOTE: Remove { get; set; } from the player class. If you have { get; set; }, it won't work. Unity's JsonUtility does NOT work with class members that are defined as properties.

Answer 2

Assume you got a JSON like this

[
    {
        "type": "qrcode",
        "symbol": [
            {
                "seq": 0,
                "data": "HelloWorld9887725216",
                "error": null
            }
        ]
    }
]

To parse the above JSON in unity, you can create JSON model like this.

[System.Serializable]
public class QrCodeResult
{
    public QRCodeData[] result;
}

[System.Serializable]
public class Symbol
{
    public int seq;
    public string data;
    public string error;
}

[System.Serializable]
public class QRCodeData
{
    public string type;
    public Symbol[] symbol;
}

And then simply parse in the following manner...

var myObject = JsonUtility.FromJson<QrCodeResult>("{\"result\":" + jsonString.ToString() + "}");

Now you can modify the JSON/CODE according to your need. https://docs.unity3d.com/Manual/JSONSerialization.html

Answer 3

Unity <= 2019

Narottam Goyal had a good idea of wrapping the array in a json object, and then deserializing into a struct. The following uses Generics to solve this for arrays of all type, as opposed to making a new class everytime.

[System.Serializable]
private struct JsonArrayWrapper<T> {
    public T wrap_result;
}

public static T ParseJsonArray<T>(string json) {
    var temp = JsonUtility.FromJson<JsonArrayWrapper<T>>("{\"wrap_result\":" + json + "}");
    return temp.wrap_result;
}

It can be used in the following way:

string[] options = ParseJsonArray<string[]>(someArrayOfStringsJson);

Unity 2020

In Unity 2020 there is an official newtonsoft package which is a far better json library.

Answer 4

you have to add [System.Serializable] to PlayerItem class ,like this:

using System;
[System.Serializable]
public class PlayerItem   {
    public string playerId;
    public string playerLoc;
    public string playerNick;
}

Answer 5

Like @Maximiliangerhardt said, MiniJson do not have the capability to deserialize properly. I used JsonFx and works like a charm. Works with the []

player[] p = JsonReader.Deserialize<player[]>(serviceData);
Debug.Log(p[0].playerId +" "+ p[0].playerLoc+"--"+ p[1].playerId + " " + p[1].playerLoc+"--"+ p[2].playerId + " " + p[2].playerLoc);

Answer 6

To Read JSON File, refer this simple example

Your JSON File (StreamingAssets/Player.json)

{
    "Name": "MyName",
    "Level": 4
}

C# Script

public class Demo
{
    public void ReadJSON()
    {
        string path = Application.streamingAssetsPath + "/Player.json";
        string JSONString = File.ReadAllText(path);
        Player player = JsonUtility.FromJson<Player>(JSONString);
        Debug.Log(player.Name);
    }
}

[System.Serializable]
public class Player
{
    public string Name;
    public int Level;
}

Answer 7

You can use Newtonsoft.Json just add Newtonsoft.dll to your project and use below script

using System;
using Newtonsoft.Json;
using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{

    [Serializable]
    public class Person
    {
        public string id;
        public string name;
    }
    public Person[] person;

    private void Start()
    {
       var myjson = JsonConvert.SerializeObject(person);

        print(myjson);

    }
}

another solution is using JsonHelper

using System;
using Newtonsoft.Json;
using UnityEngine;

public class NewBehaviourScript : MonoBehaviour
{

    [Serializable]
    public class Person
    {
        public string id;
        public string name;
    }
    public Person[] person;

    private void Start()
    {
        var myjson = JsonHelper.ToJson(person);

        print(myjson);

    }
}

Answer 8

If you came here looking for how to serialize a List using JsonUtility without any extra packages, read on.

[System.Serializable]
public class JsonableListWrapper<T>
{
    public List<T> list;
    public JsonableListWrapper(List<T> list) => this.list = list;
}

Example usage:

List<string> stringList = new List<string>(){"one","two","three"};
// To Json
string stringListAsJson = JsonUtility.ToJson(new JsonListWrapper<string>(stringList));
// From Json
List<string> stringListFromJson = JsonUtility.FromJson<JsonListWrapper<string>>(stringListAsJson).list;

Credit to theonlysake from this thread: https://forum.unity.com/threads/jsonutilities-tojson-with-list-string-not-working-as-expected.722783/

It seems you can't serialize/deserialize a List directly, but if it's a property of a class you can. In my own personal case, I replaced the string type with the type of a custom class and it worked great.

Answer 9

Don't trim the [] and you should be fine. [] identify a JSON array which is exactly what you require to be able to iterate its elements.

Answer 10

IF you are using Vector3 this is what i did

1- I create a class Name it Player

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
[Serializable]
public class Player
{
    public Vector3[] Position;

}

2- then i call it like this

if ( _ispressed == true)
        {
            Player playerInstance = new Player();
            playerInstance.Position = newPos;
            string jsonData = JsonUtility.ToJson(playerInstance);

            reference.Child("Position" + Random.Range(0, 1000000)).SetRawJsonValueAsync(jsonData);
            Debug.Log(jsonData);
            _ispressed = false;
        }

3- and this is the result

"Position":[ {"x":-2.8567452430725099,"y":-2.4323320388793947,"z":0.0}]}