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{ /// /// MongoDbCsharpHelper:MongoDb基于C#语言操作帮助类 /// Author:Zuowenjun /// Date:2017/11/16 /// 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 .Filter.Eq("name", collectionName) }; return database.ListCollections(options).ToEnumerable().Any(); } private MongoDB.Driver.IMongoCollection GetMongoCollection (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 (name, settings); } private List > BuildUpdateDefinition (object doc, string parent) { var updateList = new List >(); 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 (doc, string.Format("{0}.{1}", key, i))); } else { updateList.Add(Builders .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 .Update.Set(string.Format("{0}.{1}", key, sub.Name), sub.GetValue(subObj))); } #endregion } } else //简单类型 { updateList.Add(Builders .Update.Set(key, property.GetValue(doc))); } } return updateList; } private void CreateIndex (IMongoCollection col, string[] indexFields, CreateIndexOptions options = null) { if (indexFields == null) { return; } var indexKeys = Builders .IndexKeys; IndexKeysDefinition 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 (string collectionName, string[] indexFields, CreateIndexOptions options = null) { CreateIndex(GetMongoCollection (collectionName), indexFields, options); } public void CreateCollection (string[] indexFields = null, CreateIndexOptions options = null) { string collectionName = typeof(TDoc).Name; CreateCollection (collectionName, indexFields, options); } public void CreateCollection (string collectionName, string[] indexFields = null, CreateIndexOptions options = null) { var mongoDatabase = GetMongoDatabase(); mongoDatabase.CreateCollection(collectionName); CreateIndex(GetMongoCollection (collectionName), indexFields, options); } public List Find (Expression > filter, FindOptions options = null) { string collectionName = typeof(TDoc).Name; return Find (collectionName, filter, options); } public List Find (string collectionName, Expression > filter, FindOptions options = null) { var colleciton = GetMongoCollection (collectionName); return colleciton.Find(filter, options).ToList(); } public List FindByPage (Expression > filter, Expression > keySelector, int pageIndex, int pageSize, out int rsCount) { string collectionName = typeof(TDoc).Name; return FindByPage (collectionName, filter, keySelector, pageIndex, pageSize, out rsCount); } public List FindByPage (string collectionName, Expression > filter, Expression > keySelector, int pageIndex, int pageSize, out int rsCount) { var colleciton = GetMongoCollection (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 doc, InsertOneOptions options = null) { string collectionName = typeof(TDoc).Name; Insert (collectionName, doc, options); } public void Insert (string collectionName, TDoc doc, InsertOneOptions options = null) { var colleciton = GetMongoCollection (collectionName); colleciton.InsertOne(doc, options); } public void InsertMany (IEnumerable docs, InsertManyOptions options = null) { string collectionName = typeof(TDoc).Name; InsertMany (collectionName, docs, options); } public void InsertMany (string collectionName, IEnumerable docs, InsertManyOptions options = null) { var colleciton = GetMongoCollection (collectionName); colleciton.InsertMany(docs, options); } public void Update (TDoc doc, Expression > filter, UpdateOptions options = null) { string collectionName = typeof(TDoc).Name; var colleciton = GetMongoCollection (collectionName); List > updateList = BuildUpdateDefinition (doc, null); colleciton.UpdateOne(filter, Builders .Update.Combine(updateList), options); } public void Update (string collectionName, TDoc doc, Expression > filter, UpdateOptions options = null) { var colleciton = GetMongoCollection (collectionName); List > updateList = BuildUpdateDefinition (doc, null); colleciton.UpdateOne(filter, Builders .Update.Combine(updateList), options); } public void Update (TDoc doc, Expression > filter, UpdateDefinition updateFields, UpdateOptions options = null) { string collectionName = typeof(TDoc).Name; Update (collectionName, doc, filter, updateFields, options); } public void Update (string collectionName, TDoc doc, Expression > filter, UpdateDefinition updateFields, UpdateOptions options = null) { var colleciton = GetMongoCollection (collectionName); colleciton.UpdateOne(filter, updateFields, options); } public void UpdateMany (TDoc doc, Expression > filter, UpdateOptions options = null) { string collectionName = typeof(TDoc).Name; UpdateMany (collectionName, doc, filter, options); } public void UpdateMany (string collectionName, TDoc doc, Expression > filter, UpdateOptions options = null) { var colleciton = GetMongoCollection (collectionName); List > updateList = BuildUpdateDefinition (doc, null); colleciton.UpdateMany(filter, Builders .Update.Combine(updateList), options); } public void Delete (Expression > filter, DeleteOptions options = null) { string collectionName = typeof(TDoc).Name; Delete (collectionName, filter, options); } public void Delete (string collectionName, Expression > filter, DeleteOptions options = null) { var colleciton = GetMongoCollection (collectionName); colleciton.DeleteOne(filter, options); } public void DeleteMany (Expression > filter, DeleteOptions options = null) { string collectionName = typeof(TDoc).Name; DeleteMany (collectionName, filter, options); } public void DeleteMany (string collectionName, Expression > filter, DeleteOptions options = null) { var colleciton = GetMongoCollection (collectionName); colleciton.DeleteMany(filter, options); } public void ClearCollection (string collectionName) { var colleciton = GetMongoCollection (collectionName); var inddexs = colleciton.Indexes.List(); List > docIndexs = new List >(); while (inddexs.MoveNext()) { docIndexs.Add(inddexs.Current); } var mongoDatabase = GetMongoDatabase(); mongoDatabase.DropCollection(collectionName); if (!CollectionExists(mongoDatabase, collectionName)) { CreateCollection (collectionName); } if (docIndexs.Count > 0) { colleciton = mongoDatabase.GetCollection (collectionName); foreach (var index in docIndexs) { foreach (IndexKeysDefinition 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 ("SysLog1",new[]{"LogDT"}); mongoDbHelper.Find ("SysLog1", t => t.Level == "Info"); int rsCount=0; mongoDbHelper.FindByPage ("SysLog1",t=>t.Level=="Info",t=>t,1,20,out rsCount); mongoDbHelper.Insert ("SysLog1",new SysLogInfo { LogDT = DateTime.Now, Level = "Info", Msg = "测试消息" }); mongoDbHelper.Update ("SysLog1",new SysLogInfo { LogDT = DateTime.Now, Level = "Error", Msg = "测试消息2" },t => t.LogDT==new DateTime(1900,1,1)); mongoDbHelper.Delete (t => t.Level == "Info"); mongoDbHelper.ClearCollection ("SysLog1");