C# System.Text.Json Can't deserialize response from open sky api. My DTO model doesn't fit

Question

C# System.Text.Json Can't deserialize response from open sky api. My DTO model doesn't fit I have response body like this and i can't desearilize it to c# dto model:

{
    "time": 1677521877,
    "states": [
        [
            "a2e5ec",
            "SKW3744",
            "United States",
            1677521876,
            1677521876,
            -122.31,
            47.3658,
            1447.8,
            false,
            102.38,
            179.42,
            7.48,
            null,
            1280.16,
            null,
            false,
            0
        ]
    ]
}

This is my dto model for this response:

public class RootObjectOfFlightStatus
{
    [JsonPropertyName("time")]
    public long Time { get; set; }

    [JsonPropertyName("states")]
    public List<List<FlightStatusOpenSkyDto>>? States { get; set; }
}

public class FlightStatusOpenSkyDto
{
    [JsonPropertyName("0")]
    public string? Icao24 { get; set; }

    [JsonPropertyName("1")]
    public string? Callsign { get; set; }

    [JsonPropertyName("2")]
    public string? OriginCountry { get; set; }

    [JsonPropertyName("3")]
    public int? TimePosition { get; set; }

    [JsonPropertyName("4")]
    public int? LastContact { get; set; }

    [JsonPropertyName("5")]
    public float? Longitude { get; set; }

    [JsonPropertyName("6")]
    public float? Latitude { get; set; }

    [JsonPropertyName("7")]
    public float? BaroAltitude { get; set; }

    [JsonPropertyName("8")]
    public bool? OnGround { get; set; }

    [JsonPropertyName("9")]
    public float? Velocity { get; set; }

    [JsonPropertyName("10")]
    public float? TrueTrack { get; set; }

    [JsonPropertyName("11")]
    public float? VerticalRate { get; set; }

    [JsonPropertyName("12")]
    public int[]? Sensors { get; set; }

    [JsonPropertyName("13")]
    public float? GeoAltitude { get; set; }

    [JsonPropertyName("14")]
    public string? Squawk { get; set; }

    [JsonPropertyName("15")]
    public bool? Spi { get; set; }

    [JsonPropertyName("16")]
    public int? PositionSource { get; set; }

    [JsonPropertyName("17")]
    public int? Category { get; set; }
}`

`RootObjectOfFlightStatus? flightStatusOpenSkyDto = JsonSerializer.Deserialize<RootObjectOfFlightStatus>(here is respone); 

and I get

flightStatusOpenSkyDto

value always null. I'm short of ideas what is wrong here. Could you please help?

I suggest the trouble is in this line of code.

public List<List<FlightStatusOpenSkyDto>>? States { get; set; } 

I tried here several options but still get the same result:

List<FlightStatusOpenSkyDto[]>? States,
FlightStatusOpenSkyDto[][]? States 

Answer 1

Your FlightStatusOpenSkyDto class is expecting there to be JSON in the form of "0": "value", "1": "another value"... which doesn't match. Instead, you are going to have to either write your own custom converter or you could simply use object instead. For example:

public class RootObjectOfFlightStatus
{
    ...
    [JsonPropertyName("states")]
    public List<List<JsonElement>> States { get; set; }
}

Then you can do something like this:

var result = JsonSerializer.Deserialize<RootObjectOfFlightStatus>(Json);

var icao24 = result.States[0][0].GetString();
var timePosition = result.States[0][3].GetInt32();

Answer 2

You can try this code

using System.Text.Json;

var jNode = System.Text.Json.Nodes.JsonNode.Parse(json);

var arr = new JsonArray();
foreach (var jArr in jNode["states"].AsArray())
{
    var statesObj = new  Dictionary< string,JsonNode>();
        for (int i = 0; i < jArr.AsArray().Count; i++)
            statesObj.Add( i.ToString(), jArr[i]);
    arr.Add(statesObj);
}

RootObjectOfFlightStatus rootObjectOfFlightStatus = new RootObjectOfFlightStatus
{
    Time = (long)jNode["time"],
    States = arr.Deserialize <List<FlightStatusOpenSkyDto>>() 
};

and it seems to me that you have to fix your class or a json since the last positions json and class are not sync. Also fix your root class

public class RootObjectOfFlightStatus
{
    public long Time { get; set; }
    public List<FlightStatusOpenSkyDto>? States { get; set; }
}

test

var originCountry = rootObjectOfFlightStatus.States[0].OriginCountry; //"United States"

var icao24 = rootObjectOfFlightStatus.States[0].Icao24; // "a2e5ec"

FlightStatusOpenSkyDto flightStatus = rootObjectOfFlightStatus.States[0];

PropertyInfo[] properties = typeof(FlightStatusOpenSkyDto).GetProperties();
foreach (PropertyInfo prop in properties)
    Console.WriteLine(prop.Name + " : " + prop.GetValue(flightStatus));

Icao24 : a2e5ec
Callsign : SKW3744
OriginCountry : United States
TimePosition : 1677521876
LastContact : 1677521876
Longitude : -122.31
Latitude : 47.3658
BaroAltitude : 1447.8
OnGround : False
Velocity : 102.38
TrueTrack : 179.42
VerticalRate : 7.48
Sensors : 
GeoAltitude : 1280.16
Squawk : 
Spi : False
PositionSource : 0
Category :