Deserializing the JSON matchState into a custom object

[Andrey Spencer]

I'm working in Unity, and from the JSON response I get from calling AsyncMatchService.ReadMatch I want to convert the "matchState" into a custom object of type JsonMatchState. I've tried a few approaches but either get a NullReferenceException or the data populated in the JsonMatchState object is incorrect (default data).

The alternative approach I've heard is to create a new JsonMatchState and read in the values for that class one by one as a Dictionary<string, object> but I'm wondering if there's a more straightforward approach.

Here's an example of the JSON:

"data": {
	"matchState": {
		"turnNumber": 1,
		"teamTurn": 2,
		"gameState": {
			"tiles": [
				{
					"gridCoordinates": "0,3",
					"teamId": 0,
					"defenseValue": 0,
					"totalDefenseAquired": 0,
					"territoryId": 0,
					"snakeUnitId": 0,
					"snakeCarcass": false,
					"nest": false
				},
				{
					"gridCoordinates": "-2,1",
					"teamId": 0,
					"defenseValue": 0,
					"totalDefenseAquired": 0,
					"territoryId": 0,
					"snakeUnitId": 0,
					"snakeCarcass": false,
					"nest": false
				}
			]
		},
		"previousTurns": [
			{
				"teamId": 1,
				"tiles": [
					{
						"gridCoordinates": "0,1",
						"teamId": 1,
						"defenseValue": 1,
						"totalDefenseAquired": 1,
						"territoryId": 0,
						"snakeUnitId": 0,
						"snakeCarcass": false,
						"nest": false
					}
				]
			},
			{
				"teamId": 2,
				"tiles": []
			}
		]
	}
}

And here's what my classes look like:

[System.Serializable]
public class JsonMatchState
{
    public int turnNumber { get; set; }
    public int teamTurn { get; set; }
    public JsonGameState gameState { get; set; }
    public List<JsonPreviousTurn> previousTurns { get; set; }
}

[System.Serializable]
public class JsonGameState
{
    public List<JsonTile> tiles { get; set; } = new();
}

[System.Serializable]
public class JsonPreviousTurn
{
    public int teamId { get; set; } = 1;
    public List<JsonTile> tiles { get; set; } = new();
}

[System.Serializable]
public class JsonTile
{
    public string gridCoordinates { get; set; }
    public int teamId { get; set; }
    public int defenseValue { get; set; }
    public int totalDefenseAquired { get; set; }
    public int territoryId { get; set; }
    public int snakeUnitId { get; set; }
    public bool snakeCarcass { get; set; }
    public bool nest { get; set; }
}

Here are a few of the approaches I've tried:

var data = JsonReader.Deserialize<Dictionary<string, object>>(response)["data"] as Dictionary<string, object>;

//1
JsonMatchState jsonMatchState = data["matchState"] as JsonMatchState;

//2
string matchStateString = JsonConvert.SerializeObject(data["matchState"]);
JsonMatchState jsonMatchState = JsonConvert.DeserializeObject<JsonMatchState>(matchStateString);

//3
string matchStateString = JsonUtility.ToJson(data["matchState"]);
JsonMatchState jsonMatchState = JsonUtility.FromJson<JsonMatchState>(matchStateString);

//4
JsonMatchState jsonMatchState = JsonReader.Deserialize<Dictionary<string, object>>(response)["matchState"] as JsonMatchState;

[Franco Lago]

Hello Andrey and thank you for your inquiry,

For an approach like this I would recommend grabbing the matchState as a Dictionary<string,object> and then making a new instance of JsonMatchState and filling in each field one at a time.

An example of this would look like to get one of the fields:

JsonMatchState matchState = new JsonMatchState();
var matchState = data["matchState"] as Dictionary<string, object>;
matchState.turnNumber = (int) matchState["turnNumber"];

Hope this helps and please let us know if you have further questions or inquiries about this.