http://api.mongodb.com/csharp/current/html/T_MongoDB_Bson_BsonDocument.htm
如何取出document中的数据
BsonDocument book;
string author = book["author"].AsString;
DateTime publicationDate = book["publicationDate"].AsDateTime;
int pages = book["pages", -1].AsInt32; // default value is -1
原文：http://www.cnblogs.com/chucklu/p/6490756.html