Question

Consider the following C# class:

public class Role
{
    public string Id { get; set; }
    public IEnumerable<string> Users { get; set; }
}

How do I configure that Users maps to an array of ObjectIds in MongoDB using BsonClassMap.RegisterClassMap<Role>? I am able to configure that the scalar property Id maps to an ObjectId, but can’t figure out how to do the same for a sequence (array):

BsonClassMap.RegisterClassMap<Role>(m =>
    {
        m.MapIdProperty(r => r.Id).SetRepresentation(BsonType.ObjectId);
        // How do I map r.Users to an array of ObjectId??
        m.MapProperty(r => r.Users);
     });

Answer 1

The answer is to call SetSerializationOptions with a correctly initialized ArraySerializationOptions object:

BsonClassMap.RegisterClassMap<Role>(m =>
    {
        m.MapIdProperty(r => r.Id).SetRepresentation(BsonType.ObjectId);
        m.MapProperty(r => r.Users).SetSerializationOptions(
                new ArraySerializationOptions(new
                        RepresentationSerializationOptions(BsonType.ObjectId)));
     });