C#•6mo ago

JSON deserialization (proper way?)

Hi, I'm writing a client that consumes some JSON from a websocket. The socket can give multiple types of messages over it, what would be the most efficient (fastest) way to deserialize the JSON objects to classes? All the type of messages are known beforehand. The way I'm doing it now is:

var jsonObject = JsonDocument.Parse(inputJson);
IReponseObject returnObject = null;

if (jsonObject.RootElement.TryGetProperty("error", out JsonElement error))
{
    throw new Exception($"Issue found in response: \"{error.ToString()}\"");
}

if (jsonObject.RootElement.TryGetProperty("event", out JsonElement jsonEvent))
{
    switch (jsonEvent.ToString())
    {
        case "authenticate":
            returnObject = JsonSerializer.Deserialize<AuthenticatedResponse>(jsonObject);
            break;
        default:
            break;
    }
}

if (jsonObject.RootElement.TryGetProperty("action", out JsonElement jsonAction))
{
    switch (jsonAction.ToString())
    {
        case "getTime":
            responseContent = jsonObject.RootElement.GetProperty("response");
            IReponseObject = JsonSerializer.Deserialize<TimeResponse>(responseContent);

            break;
        case "getPressure":
            responseContent = jsonObject.RootElement.GetProperty("response");
            IReponseObject = new PressureResponse() { Pressures = new List<Pressure>() };
            if (responseContent.ValueKind == JsonValueKind.Object)
            {
                var pressure = JsonSerializer.Deserialize<PressureResponse>(responseContent);
                (IReponseObject as PressureResponse).Pressure.Add(Pressure);
            }
        else
        {
        var pressure = JsonSerializer.Deserialize<List<PressureResponse>>(responseContent);
                (IReponseObject as PressureResponses).Pressures.AddRange(Pressure);
        }
            break;
}

var jsonObject = JsonDocument.Parse(inputJson);
IReponseObject returnObject = null;

if (jsonObject.RootElement.TryGetProperty("error", out JsonElement error))
{
    throw new Exception($"Issue found in response: \"{error.ToString()}\"");
}

if (jsonObject.RootElement.TryGetProperty("event", out JsonElement jsonEvent))
{
    switch (jsonEvent.ToString())
    {
        case "authenticate":
            returnObject = JsonSerializer.Deserialize<AuthenticatedResponse>(jsonObject);
            break;
        default:
            break;
    }
}

if (jsonObject.RootElement.TryGetProperty("action", out JsonElement jsonAction))
{
    switch (jsonAction.ToString())
    {
        case "getTime":
            responseContent = jsonObject.RootElement.GetProperty("response");
            IReponseObject = JsonSerializer.Deserialize<TimeResponse>(responseContent);

            break;
        case "getPressure":
            responseContent = jsonObject.RootElement.GetProperty("response");
            IReponseObject = new PressureResponse() { Pressures = new List<Pressure>() };
            if (responseContent.ValueKind == JsonValueKind.Object)
            {
                var pressure = JsonSerializer.Deserialize<PressureResponse>(responseContent);
                (IReponseObject as PressureResponse).Pressure.Add(Pressure);
            }
        else
        {
        var pressure = JsonSerializer.Deserialize<List<PressureResponse>>(responseContent);
                (IReponseObject as PressureResponses).Pressures.AddRange(Pressure);
        }
            break;
}

12 Replies

Angius•6mo ago

Polymorphic deserialization?

How to serialize properties of derived classes with System.Text.Jso...

Learn how to serialize polymorphic objects while serializing to and deserializing from JSON in .NET.

Pannekoekje•6mo ago

I'm trying that

Pannekoekje•6mo ago

https://dotnetfiddle.net/TlaXnp

C# Online Compiler | .NET Fiddle

Test your C# code online with .NET Fiddle code editor.

Pannekoekje•6mo ago

But it isn't working as I expected, am I doing something wrong?

Angius•6mo ago

Define "not working as expected"

Pannekoekje•6mo ago

See the fiddle, I'd expect the given JSON to be deserialized as an "More"

Pannekoekje•6mo ago

Given the example: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/polymorphism?pivots=dotnet-8-0#polymorphic-type-discriminators I'd say I'm doing it right?

How to serialize properties of derived classes with System.Text.Jso...

Learn how to serialize polymorphic objects while serializing to and deserializing from JSON in .NET.

Pannekoekje•6mo ago

Or does it not work for JSON that hasn't been serialized by the serializer?

Angius•6mo ago

IIRC you need some type discriminator in your JSON

Pannekoekje•6mo ago

What do you mean?

Angius•6mo ago

Example from the docs

// JSON property named `$discriminator` will be the discriminator
[JsonPolymorphic(TypeDiscriminatorPropertyName = "$discriminator")]
// It will be deserialized to `ThreeDimensionalPoint` if `$discriminator` has value `"3d"`
[JsonDerivedType(typeof(ThreeDimensionalPoint), typeDiscriminator: "3d")]
public class BasePoint
{
    public int X { get; set; }
    public int Y { get; set; }
}

public sealed class ThreeDimensionalPoint : BasePoint
{
    public int Z { get; set; }
}

// JSON property named `$discriminator` will be the discriminator
[JsonPolymorphic(TypeDiscriminatorPropertyName = "$discriminator")]
// It will be deserialized to `ThreeDimensionalPoint` if `$discriminator` has value `"3d"`
[JsonDerivedType(typeof(ThreeDimensionalPoint), typeDiscriminator: "3d")]
public class BasePoint
{
    public int X { get; set; }
    public int Y { get; set; }
}

public sealed class ThreeDimensionalPoint : BasePoint
{
    public int Z { get; set; }
}

Pannekoekje•6mo ago

But that needs to be in the source JSON? As their example doesn't include it Ah, it does it seems.. Well I'll try to get this to work. Thx

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JSON deserialization (proper way?)