[API Proposal]: Allow segmented raw writes for Utf8JsonWriter.WriteBase64StringValue

[paulomorgado]

Background and motivation

To avoid extra allocations, it would be nice to able to write segmented data to Utf8JsonWriter.WriteBase64StringValue.

API Proposal

public sealed class Utf8JsonWriter : IAsyncDisposable, IDisposable
{
    public void WriteBase64StringValue (ReadOnlySequence<byte> bytes);
}

API Usage

public class Dto
{
    public ReadOnlyMemory<byte> Data { get; set; }

    public ReadOnlySequenceOfByteWrapper Wrapper { get; set; }
}

[JsonConverter(typeof(ReadOnlySequenceOfByteWrapperJsonConverter))]
public readonly struct ReadOnlySequenceOfByteWrapper(ReadOnlySequence<byte> data)
{
    [JsonIgnore]
    public ReadOnlySequence<byte> Data { get; } = data;
}

[JsonSerializable(typeof(Dto))]
public partial class Class1JsonSerializationContext : JsonSerializerContext
{
}

public class ReadOnlySequenceOfByteWrapperJsonConverter : JsonConverter<ReadOnlySequenceOfByteWrapper>
{
    public override ReadOnlySequenceOfByteWrapper Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        throw new NotImplementedException();
    }

    public override void Write(Utf8JsonWriter writer, ReadOnlySequenceOfByteWrapper value, JsonSerializerOptions options)
    {
        writer.WriteBase64StringValue(value.Data);
    }
}

Alternative Designs

No response

Risks

No response

[ghost]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Background and motivation

To avoid extra allocations, it would be nice to able to write segmented data to Utf8JsonWriter.WriteBase64StringValue.

API Proposal

public sealed class Utf8JsonWriter : IAsyncDisposable, IDisposable
{
    public void WriteBase64StringValue (ReadOnlySequence<byte> bytes);
}

API Usage

public class Dto
{
    public ReadOnlyMemory<byte> Data { get; set; }

    public ReadOnlySequenceOfByteWrapper Wrapper { get; set; }
}

[JsonConverter(typeof(ReadOnlySequenceOfByteWrapperJsonConverter))]
public readonly struct ReadOnlySequenceOfByteWrapper(ReadOnlySequence<byte> data)
{
    [JsonIgnore]
    public ReadOnlySequence<byte> Data { get; } = data;
}

[JsonSerializable(typeof(Dto))]
public partial class Class1JsonSerializationContext : JsonSerializerContext
{
}

public class ReadOnlySequenceOfByteWrapperJsonConverter : JsonConverter<ReadOnlySequenceOfByteWrapper>
{
    public override ReadOnlySequenceOfByteWrapper Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        throw new NotImplementedException();
    }

    public override void Write(Utf8JsonWriter writer, ReadOnlySequenceOfByteWrapper value, JsonSerializerOptions options)
    {
        writer.WriteBase64StringValue(value.Data);
    }
}

Alternative Designs

No response

Risks

No response

Author:	paulomorgado
Assignees:	-
Labels:	api-suggestion, area-System.Text.Json
Milestone:	-

[eiriktsarpalis]

Duplicate of #67337.