MongoDB

Store an ID

When the project references MongoDB.Bson, the generator adds a BSON serializer to each ID and registers it with [BsonSerializer]. A property of an ID type is stored as the value:

public sealed class ProjectDocument
{
    public ProjectId Id { get; set; }
    public string? Name { get; set; }
}

var project = new ProjectDocument { Id = ProjectId.FromInt32(42), Name = "Documentation" };

var document = project.ToBsonDocument();
Assert.Equal(42, document["_id"].AsInt32);

var deserialized = BsonSerializer.Deserialize<ProjectDocument>(document);
Assert.Equal(ProjectId.FromInt32(42), deserialized.Id);

An ID property named Id is the _id of the document, as for any other type.

How values are stored

• The serializer writes the value with the serializer that MongoDB uses for the underlying type. Your registrations apply: MongoDB.Bson 3 needs a representation for Guid values, such as BsonSerializer.RegisterSerializer(new GuidSerializer(GuidRepresentation.Standard)), and IDs that wrap a Guid use it.
• Int128, UInt128 and BigInteger values are stored as strings, and Half values as float (BSON double).
• A null ID of a class type is stored as null.

Use ObjectId values

An ID can wrap a MongoDB.Bson.ObjectId: [StronglyTypedId<ObjectId>]. It is stored as an ObjectId, and written as a string in JSON. See Underlying types.