Skill

system-text-json-net11

Name: system-text-json-net11
Author: .NET (Microsoft)

implement System.Text.Json APIs in .NET 11

Published by .NET (Microsoft) Updated Jul 15

Covers C# .NET Documentation JSON

Description

Provides guidance on new System.Text.Json APIs introduced in .NET 11. It covers typed JsonTypeInfo access via GetTypeInfo<T> and TryGetTypeInfo<T> on JsonSerializerOptions, and the new JsonNamingPolicy.PascalCase static property. Use when serializing or deserializing JSON in .NET 11 applications and needing typed metadata access or PascalCase property naming.

SKILL.md

System.Text.Json — .NET 11

New APIs added to System.Text.Json across .NET 11 releases.

When to Use

Serializing or deserializing JSON in a .NET 11 (or later) project
Needing strongly-typed JsonTypeInfo<T> access instead of the untyped JsonTypeInfo overload
Wanting to safely check whether type metadata is available without catching exceptions (TryGetTypeInfo<T>)
Requiring PascalCase property naming during JSON serialization

When Not to Use

The project targets .NET 10 or earlier — these APIs are not available before .NET 11
Using a JSON library that is not System.Text.Json (e.g., Newtonsoft.Json)
The existing untyped GetTypeInfo(Type) / TryGetTypeInfo(Type, ...) overloads are sufficient

Target Framework

<TargetFramework>net11.0</TargetFramework>

New APIs

Typed `JsonTypeInfo` Access

`JsonSerializerOptions.GetTypeInfo<T>()`

Returns a strongly-typed JsonTypeInfo<T> for the specified type, using the options' configured type-info resolver.

JsonTypeInfo<T> GetTypeInfo<T>()

`JsonSerializerOptions.TryGetTypeInfo<T>(out JsonTypeInfo<T>?)`

Attempts to retrieve typed metadata without throwing if the type is not resolved.

bool TryGetTypeInfo<T>(out JsonTypeInfo<T>? typeInfo)

`JsonNamingPolicy.PascalCase`

A new static property that converts property names to PascalCase during serialization.

static JsonNamingPolicy PascalCase { get; }

Examples

Get Typed JsonTypeInfo

using System.Text.Json;
using System.Text.Json.Serialization.Metadata;

var options = new JsonSerializerOptions(JsonSerializerDefaults.Web);

// Retrieve strongly-typed metadata for MyClass
JsonTypeInfo<MyClass> typeInfo = options.GetTypeInfo<MyClass>();
Console.WriteLine($"Type: {typeInfo.Type.Name}");

TryGetTypeInfo for Safe Access

using System.Text.Json;
using System.Text.Json.Serialization.Metadata;

var options = new JsonSerializerOptions(JsonSerializerDefaults.Web);

if (options.TryGetTypeInfo<MyClass>(out var info))
{
    Console.WriteLine($"Resolved type info for {info!.Type.Name}");
}
else
{
    Console.WriteLine("Type info not available");
}

PascalCase Naming Policy

using System.Text.Json;

var opts = new JsonSerializerOptions
{
    PropertyNamingPolicy = JsonNamingPolicy.PascalCase
};

var obj = new { firstName = "John", lastName = "Doe" };
string json = JsonSerializer.Serialize(obj, opts);
Console.WriteLine(json);
// Output: {"FirstName":"John","LastName":"Doe"}

Combined: Serialize with Typed Metadata

using System.Text.Json;
using System.Text.Json.Serialization.Metadata;

var options = new JsonSerializerOptions
{
    PropertyNamingPolicy = JsonNamingPolicy.PascalCase
};

JsonTypeInfo<Person> typeInfo = options.GetTypeInfo<Person>();
string json = JsonSerializer.Serialize(new Person("Jane", 30), typeInfo);
Console.WriteLine(json);
// Output: {"Name":"Jane","Age":30}

public record Person(string Name, int Age);

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