轻量级ORM框架初探-Dapper与PetaPoco的基本使用

一、EntityFramework

　　EF是传统的ORM框架，也是一个比较重量级的ORM框架。这里仍然使用EF的原因在于为了突出轻量级ORM框架的性能，所谓有对比才有更优的选择。

1.1 准备一张数据库表

　　（1）For MSSQL

CREATE TABLE [dbo].[Posts]
(
    [Id] INT NOT NULL PRIMARY KEY IDENTITY, 
    [CategoryId] INT NOT NULL, 
    [Slug] VARCHAR(120) NOT NULL,  
    [Title] NVARCHAR(100) NOT NULL, 
    [Published] DATETIME NOT NULL,
    [Excerpt] NVARCHAR(MAX) NOT NULL, 
    [Content] NVARCHAR(MAX) NOT NULL
);

　　（2）For MySQL

CREATE TABLE Posts
(
    Id INT NOT NULL PRIMARY KEY AUTO_INCREMENT, 
    CategoryId INT NOT NULL, 
    Slug VARCHAR(120) NOT NULL,  
    Title NVARCHAR(100) NOT NULL, 
    Published DATETIME NOT NULL,
    Excerpt LONGTEXT NOT NULL, 
    Content LONGTEXT NOT NULL
);

1.2 使用Model First方式创建数据模型

　　（1）通过nuget添加EF组件引用，然后创建edmx数据模型

　　（2）由于EF首次使用存在效率问题，因此采用园子里推荐的EF暖机操作作为测试首次执行的代码

    static void WarmupEntityFramework()
    {
        // EF暖机操作
        using (var db = new MyAppDBContext())
        {
            var objectContext = ((IObjectContextAdapter)db).ObjectContext;
            var mappingCollection = (System.Data.Entity.Core.Mapping.StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(System.Data.Entity.Core.Metadata.Edm.DataSpace.CSSpace);
            mappingCollection.GenerateViews(new System.Collections.Generic.List<System.Data.Entity.Core.Metadata.Edm.EdmSchemaError>());
        }
    }

　　（3）写一个读取数据的方法，遍历读取Posts表记录（该表有1万行记录）

    static void ModelFirstReadPosts()
    {
        var dbContext = new MyAppDBContext();
        foreach (var item in dbContext.Posts)
        {
            Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
        }
    }

　　（4）编写入口方法，通过Stopwatch记录测试耗时

    class Program
    {
        static Program()
        {
            WarmupEntityFramework();
        }

        static void Main(string[] args)
        {
            Stopwatch watch = new Stopwatch();
            watch.Start();
            // EF:4.9s
            ModelFirstReadPosts();
            watch.Stop();
            Console.WriteLine("Time consumed : {0} ms", watch.ElapsedMilliseconds);

            Console.ReadKey();
        }

        #region Method01.EntityFramework暖机操作
        static void WarmupEntityFramework()
        {
            // EF暖机操作
            using (var db = new MyAppDBContext())
            {
                var objectContext = ((IObjectContextAdapter)db).ObjectContext;
                var mappingCollection = (System.Data.Entity.Core.Mapping.StorageMappingItemCollection)objectContext.MetadataWorkspace.GetItemCollection(System.Data.Entity.Core.Metadata.Edm.DataSpace.CSSpace);
                mappingCollection.GenerateViews(new System.Collections.Generic.List<System.Data.Entity.Core.Metadata.Edm.EdmSchemaError>());
            }
        } 
        #endregion

        #region Method02.Model First方式读取数据库表记录
        static void ModelFirstReadPosts()
        {
            var dbContext = new MyAppDBContext();
            foreach (var item in dbContext.Posts)
            {
                Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
            }
        } 
        #endregion
    }

View Code

　　F5调试运行，首次查询结果如下图所示：

　　五次查询之后平均耗时：4.9s

二、Dapper

2.1 关于Dapper

　　Dapper是一个开源轻的量级的ORM，只有一个代码文件，完全开源，你可以放在项目里的任何位置，来实现数据到对象的ORM操作，体积小速度快。

2.2 使用Dapper

　　（1）通过nuget添加Dapper组件

　　（2）针对MSSQL的查询和新增操作

    #region Method01.读取MSSQL单张表
    // 2.7s
    static void DapperReadPosts()
    {
        using (SqlConnection connection = new SqlConnection(connStr))
        {
            var postList = connection.Query<Post>("select * from Posts");
            foreach (var item in postList)
            {
                Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
            }
        }
    }
    #endregion

    #region Method02.读取MSSQL连接查询
    // 2.6s
    static void DapperReadJoin()
    {
        using (SqlConnection connection = new SqlConnection(connStr))
        {
            // 这里查询结果是动态语言类型
            var postList = connection.Query("select Id,Title,GETDATE() as PostDate from Posts");
            foreach (var item in postList)
            {
                Console.WriteLine("ID:{0},PostDate:{1}", item.Id, item.PostDate);
            }
        }
    }
    #endregion

    #region Method03.读取MSSQL多个结果集
    // 2.8s
    static void DapperReadMultiResultSet()
    {
        using (SqlConnection connection = new SqlConnection(connStr))
        {
            using (var reader = connection.QueryMultiple("select * from Posts;select 1000 as Number;"))
            {
                var postList = reader.Read<Post>();
                foreach (var item in postList)
                {
                    Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
                }
            }
        }
    }
    #endregion

    #region Method04.插入MSSQL新记录
    // 0.37s
    static void InsertPostRecord()
    {
        using (SqlConnection connection = new SqlConnection(connStr))
        {
            // 多次插入单条记录
            int count = connection.Execute("insert into Posts values(@CategoryId, @Slug, @Title, @Published, @Excerpt, @Content);", new { CategoryId = 10, Slug = "BOOK", Title = "大话设计模式", Published = DateTime.Now.AddDays(1), Excerpt = "ChengJie", Content = "Design Patterns" });
            Console.WriteLine("受影响行数:{0}", count);

            count = connection.Execute("insert into Posts values(@CategoryId, @Slug, @Title, @Published, @Excerpt, @Content);", new Post() { CategoryId = 10, Slug = "BOOK", Title = "大话数据结构", Published = DateTime.Now.AddDays(1), Excerpt = "ChengJie", Content = "Data Structure" });

            Console.WriteLine("受影响行数:{0}", count);

            // 一次插入多条记录
            IList<Post> postRecords = new List<Post>();
            postRecords.Add(new Post() { CategoryId = 10, Slug = "BOOK", Title = "构建之法-现代软件工程", Published = DateTime.Now.AddDays(1), Excerpt = "ZouXin", Content = "Software Engineering" });
            postRecords.Add(new Post() { CategoryId = 10, Slug = "BOOK", Title = "编程之美", Published = DateTime.Now.AddDays(1), Excerpt = "ZouXin", Content = "I Love Coding" });
            count = connection.Execute("insert into Posts values(@CategoryId, @Slug, @Title, @Published, @Excerpt, @Content);", postRecords);

            Console.WriteLine("受影响行数:{0}", count);
        }
    }
    #endregion

View Code

　　① 棒棒哒的地方1：读取多表连接查询

        // 这里查询结果是动态语言类型
        var postList = connection.Query("select Id,Title,GETDATE() as PostDate from Posts");
        foreach (var item in postList)
        {
            Console.WriteLine("ID:{0},PostDate:{1}", item.Id, item.PostDate);
        }

　　② 棒棒哒的地方2：读取多个查询结果集

        using (var reader = connection.QueryMultiple("select * from Posts;select 1000 as Number;"))
        {
            var postList = reader.Read<Post>();
            foreach (var item in postList)
            {
                Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
            }
        }

　　③ 棒棒哒的地方3：一次插入多条数据记录

    // 一次插入多条记录
    IList<Post> postRecords = new List<Post>();
    postRecords.Add(new Post() { CategoryId = 10, Slug = "BOOK", Title = "构建之法-现代软件工程", Published = DateTime.Now.AddDays(1), Excerpt = "ZouXin", Content = "Software Engineering" });
    postRecords.Add(new Post() { CategoryId = 10, Slug = "BOOK", Title = "编程之美", Published = DateTime.Now.AddDays(1), Excerpt = "ZouXin", Content = "I Love Coding" });
    count = connection.Execute("insert into Posts values(@CategoryId, @Slug, @Title, @Published, @Excerpt, @Content);", postRecords);

　　④ 如何跨数据库读取数据记录：依赖于抽象，不依赖于具体

    static void GetPostsCrossMultiDB()
    {
        // 依赖于抽象，不依赖于具体
        using (IDbConnection connection = DbProviderFactories.GetFactory(connSetting.ProviderName).CreateConnection())
        {
            connection.ConnectionString = connSetting.ConnectionString;
            // 使用标准SQL语句屏蔽差异
            var postList = connection.Query<Post>("select * from Posts");
            foreach (var item in postList)
            {
                Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
            }
        }
    }

　　（3）测试结果：

方法	耗时
读取MSSQL单张表	2.7s
读取MSSQL连接查询	2.6s
读取MSSQL多个结果集	2.8s
多次插入MSSQL新记录	148ms

三、PetaPoco

3.1 关于PetaPoco

　　PetaPoco是一款适用于.NET应用程序的轻型对象关系映射器。与那些功能完备的ORM（如NHibernate或Entity Framework）不同的是，PetaPoco更注重易用性和性能，而非丰富的功能。使用PetaPoco只需要引入一个C#文件，可以使用强类型的 POCO（Plain Old CLR Object），并支持使用T4模板生成的类等等。

3.2 使用PetaPoco

　　（1）通过nuget添加PetaPoco组件

　　（2）编辑Database.tt模板文件，前提是首先将连接字符串配置正确

　　（3）针对MSSQL的读取和插入操作

    private static void ReadAllPostData()
    {
        using (var context = new MyAppDBContext())
        {
            var postList = context.Query<Post>("select * from Posts");
            foreach (var item in postList)
            {
                Console.WriteLine("ID:{0},Title:{1}", item.Id, item.Title);
            }
        }
    }

    private static void InsertNewPostData()
    {
        var post = new Post
        {
            CategoryId = 1,
            Slug = "BOOK",
            Title = "Microsoft SQL Server 2008技术内幕",
            Content = Guid.NewGuid().ToString(),
            Excerpt = Guid.NewGuid().ToString(),
            Published = DateTime.Now
        };

        var count = post.Insert();

        Console.WriteLine("受影响行数：{0}", count);
    }