Sådan anvender du BsonRepresentation-attribut efter konvention, når du bruger MongoDB

Ja, det lagde jeg også mærke til. Den aktuelle implementering af StringObjectIdIdGeneratorConvention synes ikke at virke af en eller anden grund. Her er en, der virker:

public class Person
{
    public string Id { get; set; }
    public string Name { get; set; }
}

public class StringObjectIdIdGeneratorConventionThatWorks : ConventionBase, IPostProcessingConvention
{
    /// <summary>
    /// Applies a post processing modification to the class map.
    /// </summary>
    /// <param name="classMap">The class map.</param>
    public void PostProcess(BsonClassMap classMap)
    {
        var idMemberMap = classMap.IdMemberMap;
        if (idMemberMap == null || idMemberMap.IdGenerator != null)
            return;
        if (idMemberMap.MemberType == typeof(string))
        {
            idMemberMap.SetIdGenerator(StringObjectIdGenerator.Instance).SetSerializer(new StringSerializer(BsonType.ObjectId));
        }
    }
}

public class Program
{
    static void Main(string[] args)
    {
        ConventionPack cp = new ConventionPack();
        cp.Add(new StringObjectIdIdGeneratorConventionThatWorks());
        ConventionRegistry.Register("TreatAllStringIdsProperly", cp, _ => true);

        var collection = new MongoClient().GetDatabase("test").GetCollection<Person>("persons");

        Person person = new Person();
        person.Name = "Name";

        collection.InsertOne(person);

        Console.ReadLine();
    }
}