基于MongoDb官方C#驱动封装MongoDbCsharpHelper类（CRUD类）

近期工作中有使用到 MongoDb作为日志持久化对象，需要实现对MongoDb的增、删、改、查，但由于MongoDb的版本比较新，是2.4以上版本的，网上已有的一些MongoDb Helper类都是基于之前MongoDb旧的版本，无法适用于新版本的MongoDb，故我基于MongoDb官方C#驱动重新封装了MongoDbCsharpHelper类（CRUD类），完整代码如下：

using MongoDB;
using MongoDB.Bson;
using MongoDB.Driver;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Threading;
using System.Web;

namespace Zuowj.Utils
{
    /// <summary>
    /// MongoDbCsharpHelper:MongoDb基于C#语言操作帮助类
    /// Author:Zuowenjun
    /// Date:2017/11/16
    /// </summary>
    public class MongoDbCsharpHelper
    {
        private readonly string connectionString = null;
        private readonly string databaseName = null;
        private MongoDB.Driver.IMongoDatabase database = null;
        private readonly bool autoCreateDb = false;
        private readonly bool autoCreateCollection = false;

        static MongoDbCsharpHelper()
        {
            BsonDefaults.GuidRepresentation = GuidRepresentation.Standard;
        }

        public MongoDbCsharpHelper(string mongoConnStr, string dbName, bool autoCreateDb = false, bool autoCreateCollection = false)
        {
            this.connectionString = mongoConnStr;
            this.databaseName = dbName;
            this.autoCreateDb = autoCreateDb;
            this.autoCreateCollection = autoCreateCollection;
        }

        #region 私有方法

        private MongoClient CreateMongoClient()
        {
            return new MongoClient(connectionString);
        }

        private MongoDB.Driver.IMongoDatabase GetMongoDatabase()
        {
            if (database == null)
            {
                var client = CreateMongoClient();
                if (!DatabaseExists(client, databaseName) && !autoCreateDb)
                {
                    throw new KeyNotFoundException("此MongoDB名称不存在：" + databaseName);
                }

                database = CreateMongoClient().GetDatabase(databaseName);
            }

            return database;
        }

        private bool DatabaseExists(MongoClient client, string dbName)
        {
            try
            {
                var dbNames = client.ListDatabases().ToList().Select(db => db.GetValue("name").AsString);
                return dbNames.Contains(dbName);
            }
            catch //如果连接的账号不能枚举出所有DB会报错，则默认为true
            {
                return true;
            }

        }

        private bool CollectionExists(IMongoDatabase database, string collectionName)
        {
            var options = new ListCollectionsOptions
            {
                Filter = Builders<BsonDocument>.Filter.Eq("name", collectionName)
            };

            return database.ListCollections(options).ToEnumerable().Any();
        }

        private MongoDB.Driver.IMongoCollection<TDoc> GetMongoCollection<TDoc>(string name, MongoCollectionSettings settings = null)
        {
            var mongoDatabase = GetMongoDatabase();

            if (!CollectionExists(mongoDatabase, name) && !autoCreateCollection)
            {
                throw new KeyNotFoundException("此Collection名称不存在：" + name);
            }

            return mongoDatabase.GetCollection<TDoc>(name, settings);
        }

        private List<UpdateDefinition<TDoc>> BuildUpdateDefinition<TDoc>(object doc, string parent)
        {
            var updateList = new List<UpdateDefinition<TDoc>>();
            foreach (var property in typeof(TDoc).GetProperties(BindingFlags.Instance | BindingFlags.Public))
            {
                var key = parent == null ? property.Name : string.Format("{0}.{1}", parent, property.Name);
                //非空的复杂类型
                if ((property.PropertyType.IsClass || property.PropertyType.IsInterface) && property.PropertyType != typeof(string) && property.GetValue(doc) != null)
                {
                    if (typeof(IList).IsAssignableFrom(property.PropertyType))
                    {
                        #region 集合类型
                        int i = 0;
                        var subObj = property.GetValue(doc);
                        foreach (var item in subObj as IList)
                        {
                            if (item.GetType().IsClass || item.GetType().IsInterface)
                            {
                                updateList.AddRange(BuildUpdateDefinition<TDoc>(doc, string.Format("{0}.{1}", key, i)));
                            }
                            else
                            {
                                updateList.Add(Builders<TDoc>.Update.Set(string.Format("{0}.{1}", key, i), item));
                            }
                            i++;
                        }
                        #endregion
                    }
                    else
                    {
                        #region 实体类型
                        //复杂类型，导航属性，类对象和集合对象
                        var subObj = property.GetValue(doc);
                        foreach (var sub in property.PropertyType.GetProperties(BindingFlags.Instance | BindingFlags.Public))
                        {
                            updateList.Add(Builders<TDoc>.Update.Set(string.Format("{0}.{1}", key, sub.Name), sub.GetValue(subObj)));
                        }
                        #endregion
                    }
                }
                else //简单类型
                {
                    updateList.Add(Builders<TDoc>.Update.Set(key, property.GetValue(doc)));
                }
            }

            return updateList;
        }

        private void CreateIndex<TDoc>(IMongoCollection<TDoc> col, string[] indexFields, CreateIndexOptions options = null)
        {
            if (indexFields == null)
            {
                return;
            }
            var indexKeys = Builders<TDoc>.IndexKeys;
            IndexKeysDefinition<TDoc> keys = null;
            if (indexFields.Length > 0)
            {
                keys = indexKeys.Descending(indexFields[0]);
            }
            for (var i = 1; i < indexFields.Length; i++)
            {
                var strIndex = indexFields[i];
                keys = keys.Descending(strIndex);
            }

            if (keys != null)
            {
                col.Indexes.CreateOne(keys, options);
            }

        }

        #endregion

        public void CreateCollectionIndex<TDoc>(string collectionName, string[] indexFields, CreateIndexOptions options = null)
        {
            CreateIndex(GetMongoCollection<TDoc>(collectionName), indexFields, options);
        }

        public void CreateCollection<TDoc>(string[] indexFields = null, CreateIndexOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            CreateCollection<TDoc>(collectionName, indexFields, options);
        }

        public void CreateCollection<TDoc>(string collectionName, string[] indexFields = null, CreateIndexOptions options = null)
        {
            var mongoDatabase = GetMongoDatabase();
            mongoDatabase.CreateCollection(collectionName);
            CreateIndex(GetMongoCollection<TDoc>(collectionName), indexFields, options);
        }

        public List<TDoc> Find<TDoc>(Expression<Func<TDoc, bool>> filter, FindOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            return Find<TDoc>(collectionName, filter, options);
        }

        public List<TDoc> Find<TDoc>(string collectionName, Expression<Func<TDoc, bool>> filter, FindOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            return colleciton.Find(filter, options).ToList();
        }

        public List<TDoc> FindByPage<TDoc, TResult>(Expression<Func<TDoc, bool>> filter, Expression<Func<TDoc, TResult>> keySelector, int pageIndex, int pageSize, out int rsCount)
        {
            string collectionName = typeof(TDoc).Name;
            return FindByPage<TDoc, TResult>(collectionName, filter, keySelector, pageIndex, pageSize, out rsCount);
        }

        public List<TDoc> FindByPage<TDoc, TResult>(string collectionName, Expression<Func<TDoc, bool>> filter, Expression<Func<TDoc, TResult>> keySelector, int pageIndex, int pageSize, out int rsCount)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            rsCount = colleciton.AsQueryable().Where(filter).Count();

            int pageCount = rsCount / pageSize + ((rsCount % pageSize) > 0 ? 1 : 0);
            if (pageIndex > pageCount) pageIndex = pageCount;
            if (pageIndex <= 0) pageIndex = 1;

            return colleciton.AsQueryable(new AggregateOptions { AllowDiskUse = true }).Where(filter).OrderByDescending(keySelector).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
        }

        public void Insert<TDoc>(TDoc doc, InsertOneOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            Insert<TDoc>(collectionName, doc, options);
        }

        public void Insert<TDoc>(string collectionName, TDoc doc, InsertOneOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            colleciton.InsertOne(doc, options);
        }

        public void InsertMany<TDoc>(IEnumerable<TDoc> docs, InsertManyOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            InsertMany<TDoc>(collectionName, docs, options);
        }

        public void InsertMany<TDoc>(string collectionName, IEnumerable<TDoc> docs, InsertManyOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            colleciton.InsertMany(docs, options);
        }

        public void Update<TDoc>(TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            List<UpdateDefinition<TDoc>> updateList = BuildUpdateDefinition<TDoc>(doc, null);
            colleciton.UpdateOne(filter, Builders<TDoc>.Update.Combine(updateList), options);
        }

        public void Update<TDoc>(string collectionName, TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            List<UpdateDefinition<TDoc>> updateList = BuildUpdateDefinition<TDoc>(doc, null);
            colleciton.UpdateOne(filter, Builders<TDoc>.Update.Combine(updateList), options);
        }

        public void Update<TDoc>(TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateDefinition<TDoc> updateFields, UpdateOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            Update<TDoc>(collectionName, doc, filter, updateFields, options);
        }

        public void Update<TDoc>(string collectionName, TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateDefinition<TDoc> updateFields, UpdateOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            colleciton.UpdateOne(filter, updateFields, options);
        }

        public void UpdateMany<TDoc>(TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            UpdateMany<TDoc>(collectionName, doc, filter, options);
        }

        public void UpdateMany<TDoc>(string collectionName, TDoc doc, Expression<Func<TDoc, bool>> filter, UpdateOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            List<UpdateDefinition<TDoc>> updateList = BuildUpdateDefinition<TDoc>(doc, null);
            colleciton.UpdateMany(filter, Builders<TDoc>.Update.Combine(updateList), options);
        }

        public void Delete<TDoc>(Expression<Func<TDoc, bool>> filter, DeleteOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            Delete<TDoc>(collectionName, filter, options);
        }

        public void Delete<TDoc>(string collectionName, Expression<Func<TDoc, bool>> filter, DeleteOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            colleciton.DeleteOne(filter, options);
        }

        public void DeleteMany<TDoc>(Expression<Func<TDoc, bool>> filter, DeleteOptions options = null)
        {
            string collectionName = typeof(TDoc).Name;
            DeleteMany<TDoc>(collectionName, filter, options);
        }

        public void DeleteMany<TDoc>(string collectionName, Expression<Func<TDoc, bool>> filter, DeleteOptions options = null)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            colleciton.DeleteMany(filter, options);
        }

        public void ClearCollection<TDoc>(string collectionName)
        {
            var colleciton = GetMongoCollection<TDoc>(collectionName);
            var inddexs = colleciton.Indexes.List();
            List<IEnumerable<BsonDocument>> docIndexs = new List<IEnumerable<BsonDocument>>();
            while (inddexs.MoveNext())
            {
                docIndexs.Add(inddexs.Current);
            }
            var mongoDatabase = GetMongoDatabase();
            mongoDatabase.DropCollection(collectionName);

            if (!CollectionExists(mongoDatabase, collectionName))
            {
                CreateCollection<TDoc>(collectionName);
            }

            if (docIndexs.Count > 0)
            {
                colleciton = mongoDatabase.GetCollection<TDoc>(collectionName);
                foreach (var index in docIndexs)
                {
                    foreach (IndexKeysDefinition<TDoc> indexItem in index)
                    {
                        try
                        {
                            colleciton.Indexes.CreateOne(indexItem);
                        }
                        catch
                        { }
                    }
                }
            }

        }
    }
}

对上述代码中几个特别的点进行简要说明：

1.由于MongoClient.GetDatabase 获取DB、MongoClient.GetCollection<TDoc> 获取文档（也可称为表）的方法 都有一个特点，即：如果指定的DB名称、Collection名称不存在，则会直接创建，但有的时候可能是因为DB名称、Collection名称写错了导致误创建了的DB或Collection，那就引起不必要的麻烦，故在MongoDbCsharpHelper类类内部封装了两个私有的方法：DatabaseExists（判断DB是否存在，如是连接的账号没有检索DB的权限可能会报错，故代码中加了直接返回true）、CollectionExists（判断Collection是否存在）；

2.每个CRUD方法，我都分别重载了两个方法，一个是无需指定Collection名称，一个是需要指定Collection名称，为什么这么做呢？原因很简单，因为有时Collection的结构是相同的但又是不同的Collection，这时TDoc是同一个实体类，但collectionName却是不同的；

3.分页查询的时候如果Collection的数据量比较大，那么就会报类似错误：exception: Sort exceeded memory limit of 104857600 bytes, but did not opt in to external sorting. Aborting operation. Pass allowDiskUse:true，根据报错提示，我们在查询大数据量时增加AggregateOptions对象，如： colleciton.AsQueryable(new AggregateOptions { AllowDiskUse = true })

4.ClearCollection清除Collection的所有数据，如果Collection的数据量非常大，那么直接使用colleciton.DeleteMany可能需要很久，有没有类似SQL SERVER 的truncate table的方法呢？经过多方论证，很遗憾并没有找到同类功能的方法，只有DropCollection方法，而这个DropCollection方法是直接删除Collection，当然包括Collection的所有数据，效率也非常高，但是由于是Drop，Collection就不存在了，如果再访问有可能会报Collection不存在的错误，那有没有好的办法解决了，当然有，那就是先DropCollection 然后再CreateCollection，最后别忘了把原有的索引插入到新创建的Collection中，这样就实现了truncate 初始化表的作用，当然在创建索引的时候，有的时候可能报报错（如：_id），因为_id默认就会被创建索引，再创建可能就会报错，故colleciton.Indexes.CreateOne外我加了try catch，如果报错则忽略。

5.CreateCollection（创建集合）、CreateCollectionIndex（创建集合索引）因为有的时候我们需要明确的去创建一个Collection或对已有的Collection创建索引，如果通过shell命令会非常不方便，故在此封装了一下。

使用示例如下：

            var mongoDbHelper = new MongoDbCsharpHelper("MongoDbConnectionString", "LogDB");

            mongoDbHelper.CreateCollection<SysLogInfo>("SysLog1",new[]{"LogDT"});

            mongoDbHelper.Find<SysLogInfo>("SysLog1", t => t.Level == "Info");

            int rsCount=0;
            mongoDbHelper.FindByPage<SysLogInfo, SysLogInfo>("SysLog1",t=>t.Level=="Info",t=>t,1,20,out rsCount);

            mongoDbHelper.Insert<SysLogInfo>("SysLog1",new SysLogInfo { LogDT = DateTime.Now, Level = "Info", Msg = "测试消息" });

            mongoDbHelper.Update<SysLogInfo>("SysLog1",new SysLogInfo { LogDT = DateTime.Now, Level = "Error", Msg = "测试消息2" },t => t.LogDT==new DateTime(1900,1,1));

            mongoDbHelper.Delete<SysLogInfo>(t => t.Level == "Info");

            mongoDbHelper.ClearCollection<SysLogInfo>("SysLog1");