Catch up with .NET Core - System.Text.JSON

April 27th, 2020

TL;DR

Introduction to System.Text.Json. Basically, the article is a projection of documentation from microsoft docs, you might want to skip this one 😛. It was created due to the habit of learning new stuff that I practice.

For a very long time .NET Framework didn’t have a unanimous and centralized built-in API to work with JSON. Also, the way we work with JSON has shaped and evolved over time. So .NET team has added brand-new NuGet package System.Text.Json with support of serialization of object to JSON text, deserialization to JSON text to objects, reading/writing JSON text encoded as UTF-8 and creation of in-memory JSON (DOM) objects. By default, strings .NET are represented by UTF-16 encoding. System.Text.Json avoids unnecessary transcoding by making use of ref struct and working with UTF-8 in place.

Also, System.Text.Json eliminates dependency on 3rd party library for ASP .NET Core. Application developers still could easily use Json.NET, but this time there is not dependency between underlying platform and application code.

Examples. JSON ↔ POCO

Excessive description how to serialize could be found at:

private static void SerializePrettyPrint()
{
    var payload = new DataPayload()
    {
        Id = 1,
        Type = Type.Root,
        Descendants = new DataPayload[]{
            new DataPayload(){Id = 2, Type = Type.Standard}
        }
    };
    var options = new JsonSerializerOptions
    {
        WriteIndented = true,
        AllowTrailingCommas = true,
        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
        IgnoreNullValues = true,
        Converters = { new JsonStringEnumConverter(JsonNamingPolicy.CamelCase) }
    };
    string payloadAsText = JsonSerializer.Serialize(payload, options);
    Trace.TraceInformation(payloadAsText);
    var payload2 = JsonSerializer.Deserialize<DataPayload>(payloadAsText, options);
    Debug.Assert(payload2.Id == payload.Id, "same id");
    Debug.Assert(payload2.Type == Type.Root, "same id");
}