MongoDB.Driver 2.4以上版本 在.NET中的基本操做

MongoDB.Driver是操做mongo數據庫的驅動，最近2.0如下版本已經從GitHub和Nuget中移除了，也就是說.NET Framework4.0再也不能從官方獲取到MongoDB的驅動了，其次MongoDB.Driver2.0開始API變動巨大，本文不適用MongoDB.Driver2.0如下版本，亦不適用.NET Framework4.5如下版本

要在.NET中使用MongoDB，就必須引用MongoDB的驅動，使用Nuget安裝MongoDB.Driver是最方便的，目前Nuget支持的MongoDB程序包有對.NET Framework4.5以上版本的依賴

安裝完成以後會在引用中新增三個MongoDB的程序集引用，其中MongoDB.Driver.Core在2.0版本如下是沒有的

先構建一個實體基類，由於Mongo要求每一個文檔都有惟一Id,默認爲ObjectId類型（根據時間Mac地址Pid算出來的，相似GUID，適用於分佈式），在這個基類中添加Id屬性

using MongoDB.Bson;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    /// <summary>
    /// 自定義類型Id
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public abstract class BaseEntity<T>
    {
        public T Id { get; set; }
    }
    /// <summary>
    /// Mongo默認填充ObjectId類型的Id
    /// </summary>
    public abstract class DefaultIdEntity : BaseEntity<ObjectId>
    {
    }
}

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開始構建數據庫訪問類DbContext

using MongoDB.Driver;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    public class DbContext
    {
        public readonly IMongoDatabase _db;
        public DbContext()
        {
            //此爲開啓驗證模式 必需使用用戶名 密碼 及指定登錄的數據庫 可採用,分割鏈接多個數據庫
            var client = new MongoClient("mongodb://root:123456@192.168.20.54:27017/admin");
            //未開啓驗證模式數據庫鏈接
            // var client = new MongoClient("mongodb://127.0.0.1:27017"); 
            //指定要操做的數據庫
            _db = client.GetDatabase("mytest");
        }

        private static string InferCollectionNameFrom<T>()
        {
            var type = typeof(T);
            return type.Name;
        }

        public IMongoCollection<T> Collection<T, TId>() where T : BaseEntity<TId>
        {
            var collectionName = InferCollectionNameFrom<T>();
            return _db.GetCollection<T>(collectionName);
        }
        /// <summary>
        /// 實體類名和數據庫中文檔（關係型數據庫中的表）名一致時使用
        /// </summary>
        public IMongoCollection<T> Collection<T>() where T : DefaultIdEntity
        {
            var collectionName = InferCollectionNameFrom<T>();
            return _db.GetCollection<T>(collectionName);
        }

        public IMongoCollection<T> Collection<T, TId>(string collectionName) where T : BaseEntity<TId>
        {
            return _db.GetCollection<T>(collectionName);
        }
        /// <summary>
        /// 實體類名和數據庫中文檔（關係型數據庫中的表）不一致時使用，經過collectionName指定要操做得文檔
        /// </summary>
        public IMongoCollection<T> Collection<T>(string collectionName) where T : DefaultIdEntity
        {
            return _db.GetCollection<T>(collectionName);
        }
    }
}

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現有數據庫數據 文檔book 包含數據以下

開始構建與文檔對應的實體，mongo是文檔數據庫，對單詞得大小寫是敏感得，因此構建的實體的字段也應該是小寫的，有點不符合習慣

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    public class book : DefaultIdEntity
    {
        public string title { get; set; }
        public double price { get; set; }
        public string author { get; set; }
        public string publisher { get; set; }
        public int saleCount { get; set; }
    }
}

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如今開始增刪查改操做，其中查找和刪除的filter參數有兩種形式，lambda和Definition

using MongoDB.Driver;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    public class OperatDb
    {
        static IMongoCollection<book> bookDao;
        static OperatDb()
        {
            bookDao = new DbContext().Collection<book>();
        }

        public static void Excute()
        {
            Console.WriteLine();
            QueryAll();
            Console.WriteLine();
            Query();
            Console.WriteLine();
            Insert();
            Console.WriteLine();
            QueryAll();
            Console.WriteLine();
            Update();
            Console.WriteLine();
            Delete();
            Console.WriteLine();
            QueryAll();
            Console.ReadKey();
        }
        public static void QueryAll()
        {
            var books = bookDao.Find(x => true).ToList();
            foreach (var item in books)
            {
                Console.WriteLine(item.ToString());
            }
        }

        public static void Query(System.Linq.Expressions.Expression<Func<book, bool>> filter = null)
        {
            if (filter == null) filter = x => x.author == "韓寒";
            var books = bookDao.Find(filter).ToList();
            foreach (var item in books)
            {
                Console.WriteLine(item.ToString());
            }
        }

        public static void Update()
        {
            var filter = Builders<book>.Filter.Eq(x => x.title, "悲傷逆流成河");
            var book = bookDao.Find(filter).FirstOrDefault();
            Console.WriteLine("更新前：{0}", book.ToString());
            var update = Builders<book>.Update.Set(x => x.publisher, "新時代出版社")
                                              .Set(x => x.price, 35)
                                              .Inc(x => x.saleCount, 10);
            var result = bookDao.UpdateOne(filter, update);
            Console.WriteLine("IsAcknowledged:{0} MatchedCount:{1} UpsertedId:{2} IsModifiedCountAvailable:{3} ModifiedCount:{4}",
                result.IsAcknowledged, result.MatchedCount, result.UpsertedId, result.IsModifiedCountAvailable, result.ModifiedCount);
            book = bookDao.Find(filter).FirstOrDefault();
            Console.WriteLine("更新後：{0}", book.ToString());
        }

        public static void Delete()
        {
            var result = bookDao.DeleteOne(x => x.title == "悲傷逆流成河");
            Console.WriteLine("DeletedCount:{0} IsAcknowledged:{1} ", result.DeletedCount, result.IsAcknowledged);
        }

        public static void Insert()
        {
            var bookInfo = new book
            {
                Id = new MongoDB.Bson.ObjectId(),
                author = "郭敬明",
                price = 10.00,
                publisher = "春風文藝出版社",
                saleCount = 0,
                title = "悲傷逆流成河"
            };
            bookDao.InsertOne(bookInfo);
        }
    }
}

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 由於我對book類的ToString方法進行了重寫，因此輸出結果以下

上面都是用的數據庫和實體字段名一致的狀況，若是不一致怎麼辦呢，Xml和Json等序列化都有標籤特性能夠用別名，Bson確定也會有，新建BookInfo實體以下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    public class BookInfo : DefaultIdEntity
    {
        public string Title { get; set; }
        public double Price { get; set; }
        public string Author { get; set; }
        public string Publisher { get; set; }
        public int SaleCount { get; set; }
    }
}

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將上面執行操做的book所有替換成BookInfo試試，發現沒報錯，再去數據庫看看會發現，數據庫新增了一個文檔，咱們預期得結果是要操做在book上，顯然這不是咱們想要的

如今將調用Collection調用改成指定collectionName爲book的形式

        static IMongoCollection<BookInfo> bookDao;
        static OperatDb()
        {
            bookDao = new DbContext().Collection<BookInfo>("book");
        }

再次運行程序，發現報錯了，文檔節點和實體字段不匹配

如今給BookInfo的字段都加上Bson的標籤特性

using MongoDB.Bson.Serialization.Attributes;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MongoTest
{
    public class BookInfo : DefaultIdEntity
    {
        [BsonElement("title")]
        public string Title { get; set; }
        [BsonElement("price")]
        public double Price { get; set; }
        [BsonElement("author")]
        public string Author { get; set; }
        [BsonElement("publisher")]
        public string Publisher { get; set; }
        [BsonElement("saleCount")]
        public int SaleCount { get; set; }
    }
}

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如今一切正常了，顯示結果和以前的同樣就再也不貼圖了，有子文檔的數據操做與此相似，譬若有以下數據

構建實體以下

  public class Director : Entity
    {
        [BsonElement("name")]
        public string Name { get; set; }
        [BsonElement("country")]
        public string Country { get; set; }
        [BsonElement("age")]
        public int Age { get; set; }
        [BsonElement("movies")]
        public List<Movie> Movies { get; set; }
    }
    public class Movie
    {
        [BsonElement("name")]
        public string Name { get; set; }
        [BsonElement("year")]
        public int Year { get; set; }
    }

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