MongoDB c# Deserialization - property not recognized

Question

I'm upgrading from using BsonDocument everywhere, to using deserialization on POCO objects.

Overall the objects are populated with correct values, but i'm having a problem with the code below, values on the EventReferenceEntry.Id property - which are always 0.

Perhaps worth knowing, is that if i remove "BsonIgnoreExtraElements" attribute from the EventReferenceEntry class, i get an error "Element 'i' does not match any field or property of class "

I've also tried setting EventReferenceEntry.Id to Int64 and UInt64, but no difference.

The driver is version 2.7.3, i tried it with a fresh installation of the latest version, but it's the same problem.

The database is a series of events. An event has: _id = Int64 _t = Int32 (the type of the event) _r = an array of objects (references to other objects, entities or events, that are relevant.)

C# Code of the POCO objects

    [BsonIgnoreExtraElements]
    public class EventEntry
    {
        [BsonElement("_id")]
        public ulong Id { get; set; }

        [BsonElement("_t")]
        public int Type { get; set; }

        public DateTime Time { get { return new DateTime((long)Id, DateTimeKind.Utc); } }

        [BsonElement("_r")]
        public List<EventReferenceEntry> References { get; set; }

    }

    [BsonIgnoreExtraElements]
    public class EventReferenceEntry
    {
        [BsonElement("i")]
        public UInt64 Id { get; set; }

        [BsonElement("n")]
        public string Name { get; set; }

        [BsonElement("a")]
        public int Asset { get; set; }

        public EventReferenceEntry()
        {
        }
    }

An example database entry

{
"_id" : NumberLong(637684658186492532),
"_t" : 1058,
"_r" : [ 
    {
        "n" : "p",
        "i" : NumberLong(637662370697662760)
    }, 
    {
        "n" : "a",
        "a" : 1202
    }, 
    {
        "n" : "o",
        "i" : NumberLong(637684655676255124),
        "a" : 2934
    }
]
}

Answer 1

Found the problem and solution.

A property in the class (in my case EventReferenceEntry) cannot be named “Id” or “id”, I guess that a property named that is assumed to be bound to the _id bson property. It can however be named “ID” or “Ident” or anything else, and the value gets assigned.