JSON.NET cast error when serializing Mongo ObjectId

Question

I am playing around with MongoDB and have an object with a mongodb ObjectId on it. When I serialise this with the .NET Json() method, all is good (but the dates are horrible

Answer 1

You can use .NET string type instead of ObjectId, You just need to decorate it with BsonRepresentation. If you use BsonDateTime, you will have the same conversion issue. This is a domain class in my project that uses those decorators.

public class DocumentMetadata
{
    [BsonId]
    [BsonRepresentation(BsonType.ObjectId)]
    public string Id { get; set; }
    public string Name { get; set; }
    public string FullName { get; set; }

    [BsonDateTimeOptions(Kind = DateTimeKind.Utc)]
    public DateTime DownloadTime { get; set; }
}