MiniBson

A minimal, trimmable, AOT-compatible BSON reader/writer library for .NET without reflection.

Features

• No reflection - Fully compatible with .NET Native AOT and trimming
• Low-level API - Forward-only reader and writer for maximum control
• Standards compliant - Implements the BSON specification
• Minimal dependencies - Only System.Memory for netstandard2.0

Installation

Regular Package

dotnet add package MiniBson

Source-Only Package

For scenarios where you want the source compiled directly into your assembly (useful for avoiding dependency conflicts or further customization):

dotnet add package MiniBson.Source

Usage

Writing BSON

using MiniBson;

using var stream = new MemoryStream();
using var writer = new BsonWriter(stream);

writer.WriteStartDocument();
writer.WriteString("name", "John Doe");
writer.WriteInt32("age", 30);
writer.WriteBoolean("active", true);
writer.WriteStartArray("tags");
writer.WriteString("developer");
writer.WriteString("gamer");
writer.WriteEndArray();
writer.WriteEndDocument();

byte[] bsonData = stream.ToArray();

Reading BSON

using MiniBson;

using var reader = new BsonReader(bsonData);
reader.ReadStartDocument();

while (reader.Read())
{
    Console.WriteLine($"{reader.CurrentName}: {reader.CurrentType}");
    
    switch (reader.CurrentType)
    {
        case BsonType.String:
            Console.WriteLine($"  Value: {reader.ReadString()}");
            break;
        case BsonType.Int32:
            Console.WriteLine($"  Value: {reader.ReadInt32()}");
            break;
        case BsonType.Boolean:
            Console.WriteLine($"  Value: {reader.ReadBoolean()}");
            break;
        case BsonType.Array:
            reader.ReadStartArray();
            while (reader.Read())
            {
                Console.WriteLine($"    Item: {reader.ReadString()}");
            }
            reader.ReadEndDocument();
            break;
        default:
            reader.Skip();
            break;
    }
}

reader.ReadEndDocument();

Supported BSON Types

Type	Write Method	Read Method
Double	WriteDouble	ReadDouble
String	WriteString	ReadString
Document	WriteStartDocument	ReadStartDocument / ReadStartNestedDocument
Array	WriteStartArray	ReadStartArray
Binary	WriteBinary	ReadBinary
ObjectId	WriteObjectId	ReadObjectId
Boolean	WriteBoolean	ReadBoolean
DateTime	WriteDateTime	ReadDateTime
Null	WriteNull	(check CurrentType)
Regex	WriteRegex	ReadRegex
JavaScript	WriteJavaScript	ReadJavaScript
Int32	WriteInt32	ReadInt32
Timestamp	WriteTimestamp	ReadTimestamp
Int64	WriteInt64	ReadInt64
GUID	WriteGuid	ReadGuid

Acknowledgments

A substantial part of the code in this project was generated with assistance from Claude.

License

MIT License - see LICENSE file for details.