NuGet MongoDB.Driver

using MongoDB.Bson;
using MongoDB.Driver;
using System;

namespace MongoTest
{
    public class MongoHp
    {
        static MongoHp()
        {
            MongoDB.Bson.Serialization.BsonSerializer.RegisterSerializer(typeof(DateTime), new MongoDB.Bson.Serialization.Serializers.DateTimeSerializer(DateTimeKind.Local));
        }

        public static Tuple<MongoClient, IMongoDatabase, IMongoCollection<BaseCollect<T>>> GetCollection<T>() where T : class
        {
            MongoUrlBuilder bd = new MongoUrlBuilder();
            bd.Server = new MongoServerAddress("localhost", 27017);
            bd.MinConnectionPoolSize = 9;
            bd.MaxConnectionPoolSize = 99;

            var url = bd.ToMongoUrl();
            var client = new MongoClient(url);
            var database = client.GetDatabase("wms");
            var collection = database.GetCollection<BaseCollect<T>>(typeof(T).Name);
            return Tuple.Create(client, database, collection);
        }
    }

    public class BaseCollect<T> where T : class
    {
        public BaseCollect(T t)
        {
            this.Value = t;
        }

        public ObjectId Id { get; set; }

        public T Value { get; set; }

        public void InsertDb()
        {
            MongoHp.GetCollection<T>().Item3.InsertOne(this);
        }

        public UpdateResult UpdateDb(IMongoCollection<BaseCollect<T>> collection = null)
        {
            if (collection == null)
            {
                return MongoHp.GetCollection<T>().Item3.UpdateOne(i => i.Id == this.Id, Builders<BaseCollect<T>>.Update.Set(i => i.Value, this.Value));
            }
            return collection.UpdateOne(i => i.Id == this.Id, Builders<BaseCollect<T>>.Update.Set(i => i.Value, this.Value));
        }

    }

    class Usr
    {
        public ObjectId Id { get; set; }

        public string label { get; set; }

        public DateTime cre_time { get; set; }

        public double level { get; set; }

        public Dept OfDept { get; set; }

    }
}