Integration with MongoDB

It is possible to use value objects (VOs) in MongoDB.

To generate a converter (serializer), add the Bson conversion in the attribute, e.g.

[ValueObject<string>(conversions: Conversions.Bson)]
public partial class Name
{
    public static readonly Name NotSet = new("[NOT_SET]");
}

Now that the serializers are generated, you now need to register them. Vogen generates a static class named RegisterBsonSerializersFor[NameOfProject].

By default, this class has a static constructor that automatically registers all BSON serializers when first accessed. However, if you need to run BSON configuration before the serializers are registered, you can use the ManuallyRegisterBsonSerializers customization:

[assembly: VogenDefaults(customizations: Customizations.ManuallyRegisterBsonSerializers)]

With this flag set, Vogen generates a TryRegister() method without a static constructor, allowing you to control when registration occurs:

// Call this manually after any BSON configuration
BsonSerializationRegisterFor[YourProjectName].TryRegister();

Without the flag, the static constructor automatically calls code like:

BsonSerializer.TryRegisterSerializer(new CustomerIdBsonSerializer());
BsonSerializer.TryRegisterSerializer(new EnergyUsedBsonSerializer());

A MongoDB example is included in the source.

Below is a walkthrough of that sample.

The sample uses MongoDB to read and write entities (a Person) to a MongoDB database in a testcontainer. Note that attributes on the value objects do not specify the BSON serializer; that is specified in global config in ModuleInitializer.cs:

[ValueObject]
public readonly partial struct Age;

[ValueObject<string>]
public readonly partial struct Name;

public class Person
{
    public Name Name { get; set; }
    public Age Age { get; set; }
}

This simple example registers the serializers manually:

BsonSerializer.RegisterSerializer(new NameBsonSerializer());
BsonSerializer.RegisterSerializer(new AgeBsonSerializer());

… but it could just as easily registered them with the generated register:

BsonSerializationRegisterForVogen_Examples.TryRegister();

(replace Vogen_Examples with the name of your project)

Next, it adds a bunch of Person objects to the database, each containing value objects representing age and name, and then reads them back.

Last modified: 27 March 2026