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!

Solution 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 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.

Solution 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

Solution 3

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;
}

Solution 4

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.

Solution 5

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;
}

View more solutions

Comments

[Jon Skeet]

Why did you remove the outer [ and ]? That's what makes it a list. Just stop removing that, and deserialize it as an array or a list and I'd expect it to be fine. Please post the code that you've tried.

[Maximilian Gerhardt]

Show us the class used for deserialization. The format is weird, why is the second playerId not wrapped inside curly braces? It should deserialize to a list of something, like List<PlayerLocation>, because this is an array.

[dil33pm]

@MaximilianGerhardt Sorry the curly braces was a typo. Fixed it in the question and added the code also. Thanks.

[Maximilian Gerhardt]

I think there's something wrong with your understanding of thow this library here handles deserializiation. It isn't the usual deserialization (as you've maybe seein in Newtonsoft.Json), but the Json.Deserialize() ALWAYS returnes a IDictionary<string,object> to you and you operate on List<object>. Look at stackoverflow.com/a/22745634/5296568 . Preferably, get a better JSON deserializer which does the deserialization you're used to.

[dil33pm]

@MaximilianGerhardt I tried with IDictionary<string,object>. I am able to get the value out, but only the first KeyValuePair<>.

[dil33pm]

I am returning an array of rows of a mysql query from PHP using json_encode($row). So the response consists of multiple JSONObjects in the format [{"playerId":"1","playerLoc":"Powai"},{"playerId":"2","playe‌​rLoc":"Andheri"},{"p‌​layerId":"3","player‌​Loc":"Churchgate"}]. I tried JsonUtility, but I couldn't deserialize the objects and get individual json objects. If you can help me with that.

[Programmer]

Look at the code I posted above. It shows you three ways to do that with JsonUtility.FromJson. I forgot to tell you to remove { get; set; } from the player class. If you have { get; set; }, it wont work. Compare your player class with the one I posted above and you will understand what I am saying.

[Programmer]

No problem. I will edit this when Unity adds support for array(which is very soon) so you won't need that Helper class anymore.

[Vlady Veselinov]

It's been months and "very soon" hasn't come yet. Every web technology out there uses JSON and we still don't have this...

[Everts]

I would not go as far as to say "Forget about all the 3rd party libraries". JsonUtility has limitations. It does not return a JSON object on which you can perform actions. For instance, I get a json file and want to check whether a "success" key is available. Can't do. The JsonUtility requires the consumer knows the exact content of the json file. Also, no Dictionary converter. So it does some good things but the usage of 3rd party is still required.

[Programmer]

@Everts I know. It's a lightweight serializer. It works for 90 percent of questions asked about json on this site. For this question, it should do the job too. I modified the question to add that at the top.

[sigmaxf]

Hey @Programmer , first off, great post, I've been searching/coding for a Json array readin method for about 3 hours now. I'm new to Unity and, coming from a web background, it seems so natural to store game data into JSON format.. a bit disappointed that Unity does not have a better JSON reading/writing system out-of-the-box. So, out of the 2 options: Break pattern and make a separate JSON file for every weapon in the game + one json file to hold all references OR hack json reading it off with some extra code (JsonHelper) to read arrays, which would you say is better?

[Programmer]

Use JsonHelper. It's fine. If you create Json with it, you can also read json with it without extra steps. The only time you may need to do extra stuff is if you are receiving the json array from the server and that is included in the solution is in my answer. Another way without JsonHelper is to put the class in another class then make it a List. This has been working for most people. If you are looking for a way to save and load game data then see this. You load and save with one line of code.

[sigmaxf]

"Another way without JsonHelper is to put the class in another class then make it a List. This has been working for most people." - How would that work? This might be just what I'm looking for.

[Ruslan L.]

On the contrary, I recommend using a third-party flexible library: custom serialization / deserialization, property serialization, mapping object fields to Json fields, ignoring fields, using constructors, etc. Simply put, it does not support the JSON standard convention (ex. top level arrays). Yes, JsonUtility the fastest, but Json-serialization usually occurs during asynchronous operations or serves to save some data, and at such times several tens of milliseconds do not play a big role.

[Olivier Pons]

My webserver returns array of array of object, each object are like {"c":"xx", "d":"yy"}. You gave a lot of examples, but not array of array... may I ask you to give one? I'd like to find out how to make a working loop with this SimpleJSON.JSONNode a = SimpleJSON.JSON.Parse("[[{\"c\": 1, \"d\": 1},{\"c\": 1, \"d\": 1}]]"); My loops begin like this and are ok but i cant access the properties c and d of each object: foreach (SimpleJSON.JSONNode row in a) { foreach (SimpleJSON.JSONNode cell in row) { var j = cell.AsObject; Debug.Log(j['c']); } }

[Programmer]

You only use SimpleJSON if Unity's JsonUtility cannot serialize that. What exactly are you receiving from the server? Just post it as it is and I will help you out

[Lotan]

Just in case you want to serialize with the same JSON format [{...},{...}] but you're getting {"objectName": [{...},{...}] }}. Remember that you can "cut" the string with 2 simple lines of code in C# like: String result = JsonUtility.ToJson(list); result = result.Substring(result.IndexOf("[")); //Remove everything before [ result = result.Substring(0, result.LastIndexOf("]") + 1); //Remove everything after ]

[Gennon]

This actually works quite well, got it working with a class like Symbol that is not an array as well.

[Jean-Michaël Celerier]

I'm trying this with unity 2018 but this does not work: the arrays aren't parsed

[Akhil Gupta]

Thanks for the ref to SimpleJSON. It really saved my day.

[Akhil Gupta]

The JsonHelper didn't work for me. Probably because I was trying to serialize an array of struct, not class. I modified it to serialize each element individually, and the join them while enclosing them inside square brackets.

[Towerss]

Used in unity 2018 and 2019. Works great. Access the array data like: Debug.Log(myObject.result[0].symbol[0].data); or for(var i = 0; i <= myObject.result.Length - 1; i ++) { Debug.Log(myObject.result[i].type); } or foreach (var item in myObject.result) { Debug.Log(item.type); }

[Junaid Pathan]

@Narottam Goyal, your method is not working in some cases, also a very difficult solution for beginners, refer this answer by me on this thread link

[derHugo]

@JunedKhanMomin your answer does basically the same but without adressing the fact that this question here was about a root level array in the JSON data in specific. In general you should rather refer to Programmer's answer which is way more elaborated.

[derHugo]

What about arrays? And what does this answer add that wasn't metnioned already in the accepted answer from over 3 years ago?

[tatmanblue]

you deserve a bit coin or something for this. amazing answer!

[R2RT]

The link you provided is dead, but this link is listed as related article: docs.unity3d.com/Packages/com.unity.nuget.newtonsoft-json@2.‌​0/… with note: "This is a package intended for internal Unity Development Projects and as such this package is not supported. Use at your own risk."

[Ruzihm]

@derHugo it includes a call to File.ReadAllText which I think is helpful and no other answer mentions :)

[derHugo]

@Ruzihm well the reason why no other answer mentioned it is because this question's scope is how to (de)serialize .. not how to do FileIO ;)

[Rose]

Note that newtonsoft does not seem to be working in unity when you build on android for example. It will work on the unity editor though.. Seems a fork of newtonsoft for unity is recommended in that case stackoverflow.com/questions/59194154/…

[david.pfx]

Does that first solution still work? All I get is a null value for wrap_result.

[Justin Meiners]

@david.pfx there is a typo that has been fixed, how about now?

[david.pfx]

Sorry, can't test it, switched to Newtonsoft to keep things moving. But I'll give it another try when I have time -- I really don't want to add an unnecessary dependency.

[Yann]

Hoowwa, comment je t'aime toi !

[derHugo]

Note that in newer version Newtonsoft JSON comes semi "built-in" as a Package via the Package Manager! It is way more powerful and e.g. supports: Properties, Dictionaries, nested arrays etc

[jhchnc]

I'm sorry, but JsonUtility is not robust enough for complex scenarios.

[Peppe L-G]

Finally got serialization that supports polymorphism in Unity now thanks to this package. In Unity, just open the Package Manager windows, and then choose to add a package by name, and provide com.unity.nuget.newtonsoft-json as the name.

[Paul Masri-Stone]

SimpleJSON is no longer on Unity's pages (as they are recommending JsonUtility). However it is still available via Git: github.com/Bunny83/SimpleJSON NB: See the Github Wiki for usage details as the README is empty.

[pete]

This troubleshooting section doesn't even begin to cover all the issues a user will face when working with parent/child classes with JSONUtility. JSONUtility is buggy and shouldn't be used. I found out the hard way after hours of debugging. Someone with a similar problem in answers.unity.com/questions/1400802/…