MongoDB c# driver - Can a field called Id not be Id?

Question

More particulary, there is a class

class X {
       ....
       string Id { get; set; }
}

class Y : X {
       ObjectId MyId { get; set; }
}

Answer 1

The answer to your question is "yes, but...".

It is possible to have a member called Id which is not mapped to the _id element. For example:

public class X {
    [BsonId]
    public ObjectId MyId;
}

public class Y : X {
    public string Id;
}

However, in a class hierarchy the _id member must be at the root of the hierarchy (in other words, all members of the hierarchy must agree on using the same _id).