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serialization

9 posts

2026-11-09 csharp dotnet dotnet-11

How to skip empty string properties when serializing with System.Text.Json

System.Text.Json has no WhenWritingEmpty option, WhenWritingDefault still writes "", and a JsonConverter<string> that writes nothing produces invalid JSON. The fix is a type-info resolver modifier that sets JsonPropertyInfo.ShouldSerialize, for reflection and source-generated contexts, checked on .NET 10.0.10 and .NET 11 RC3.

2026-09-23 system-text-json csharp dotnet-10

How to serialize public fields like Vector3 and Quaternion with System.Text.Json

System.Text.Json writes Vector3 as {} and Quaternion as {"IsIdentity":false} because they store data in public fields. Here is how IncludeFields, a custom converter, a resolver modifier and source generation fix it, measured on .NET 10 and .NET 11 RC 1.

2026-09-02 migration binaryformatter serialization

Migrate off BinaryFormatter after its removal in modern .NET

BinaryFormatter's implementation was deleted in .NET 9 and still throws PlatformNotSupportedException on .NET 10 and .NET 11: how to choose a replacement serializer, read already-persisted NRBF blobs with NrbfDecoder, and what breaks in WinForms, WPF, and ResX.

2026-08-16 system-text-json csharp csharp-14

How to make System.Text.Json ignore a property that has the required modifier

[JsonIgnore] on a required member throws InvalidOperationException: marked required but does not specify a setter. Here is why the two features collide and the four ways to ignore the property anyway, measured on .NET 10.

2026-08-10 csharp dotnet dotnet-11

How to customize source-generated System.Text.Json serialization with a type-info resolver modifier

Attach a JsonTypeInfo modifier to a source-generated JsonSerializerContext in .NET 11: why new MyContext(options) silently drops it, the WithAddedModifier setup that works, the fast path you give up (measured), and the naming-policy trap that makes modifiers no-op.

2026-07-27 csharp dotnet dotnet-11

How to serialize a polymorphic type hierarchy with JsonDerivedType in System.Text.Json

A complete guide to polymorphic JSON in .NET 11: JsonDerivedType and JsonPolymorphic, why the declared type decides everything, the $type ordering rule, every exception the feature throws, the contract model for types you do not own, and what ASP.NET Core emits in OpenAPI.

2026-06-10 dotnet-11 csharp system-text-json

System.Text.Json Finally Writes JSON Lines in .NET 11 Preview 5

.NET 11 Preview 5 adds JsonSerializer.SerializeAsyncEnumerable with topLevelValues: true, so System.Text.Json can now stream JSONL out, not just read it.

2026-04-25 csharp dotnet dotnet-11

How to write a custom JsonConverter in System.Text.Json

A complete guide to writing custom JsonConverter<T> for System.Text.Json in .NET 11: when you actually need one, how to navigate Utf8JsonReader correctly, how to handle generics with JsonConverterFactory, and how to stay AOT-friendly.

2026-04-18 dotnet-11 system-text-json csharp

System.Text.Json in .NET 11 Preview 3 adds PascalCase and per-member naming policies

.NET 11 Preview 3 finishes the naming-policy story in System.Text.Json: JsonNamingPolicy.PascalCase, a member-level [JsonNamingPolicy] attribute, and a type-level [JsonIgnore] default for cleaner DTOs.