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();