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 lt string  object gt  players   Json Deserialize serviceData  as IDictionary lt string  object gt    foreach  KeyValuePair lt string  object gt  kvp in players        Debug Log string Format  Key    0   Value    1    kvp Key  kvp Value        Thanks

User · Accepted Answer

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 check out the forked version for Unity here. 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.

User · Answer

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 lt Player gt  JSONString           Debug Log player Name             System Serializable  public class Player       public string Name      public int Level

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

Unity  lt   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 lt T gt        public T wrap result     public static T ParseJsonArray lt T gt  string json        var temp   JsonUtility FromJson lt JsonArrayWrapper lt T gt  gt   quot    quot  wrap result  quot   quot    json    quot   quot        return temp wrap result     It can be used in the following way  string   options   ParseJsonArray lt string   gt  someArrayOfStringsJson    Unity 2020 In Unity 2020 there is an official newtonsoft package which is a far better json library

User · Answer

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

User · Answer

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 lt player   gt  serviceData   Debug Log p 0  playerId       p 0  playerLoc  --   p 1  playerId         p 1  playerLoc  --   p 2  playerId         p 2  playerLoc

User · Answer

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 lt QrCodeResult gt      result       jsonString ToString             Now you can modify the JSON CODE according to your need  https   docs unity3d com Manual JSONSerialization html

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