/// <summary>
        /// 插入新数据
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="collectionName"></param>
        /// <param name="entiry"></param>
        public static void InsertOne<T>(string collectionName, T entity) where T : class
        {
            using (Mongo mongo = new Mongo(connectionString))
            {
                mongo.Connect();
                IMongoDatabase friends = mongo.GetDatabase(database);
                IMongoCollection<T> categories = friends.GetCollection<T>(collectionName);
                categories.Insert(entity, true);
                mongo.Disconnect();

            }
        }