Dapper.NET——轻量ORM _dapper

【Dapper.NET——轻量ORM】相逢意气为君饮，系马高楼垂柳边。这篇文章主要讲述Dapper.NET——轻量ORM相关的知识，希望能为你提供帮助。
Dapper是一款轻量级ORM工具（Github）。如果你在小的项目中，使用Entity Framework、NHibernate 来处理大数据访问及关系映射，未免有点杀鸡用牛刀。你又觉得ORM省时省力，这时Dapper 将是你不二的选择。
1、为什么选择Dapper

轻量。只有一个文件（SqlMapper.cs），编译完成之后只有120k(好象是变胖了)
速度快。Dapper的速度接近与IDataReader，取列表的数据超过了DataTable。
支持多种数据库。Dapper可以在所有Ado.net Providers下工作，包括sqlite, sqlce, firebird, oracle, mysql, PostgreSQL and SQL Server
可以映射一对一，一对多，多对多等多种关系。
性能高。通过Emit反射IDataReader的序列队列，来快速的得到和产生对象，性能不错。
支持FrameWork2.0，3.0，3.5，4.0，4.5

2、以Dapper（4.0）为例。 2.1 在数据库中建立几张表。

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CREATE TABLE [dbo].[CICUser] ( [UserId][int] IDENTITY(1, 1) PRIMARY KEY NOT NULL, [Username][nvarchar](256) NOT NULL, [PasswordHash][nvarchar](500) NULL, [Email][nvarchar](256) NULL, [PhoneNumber][nvarchar](30) NULL, [IsFirstTimeLogin][bit] DEFAULT(1) NOT NULL, [AccessFailedCount][int] DEFAULT(0) NOT NULL, [CreationDate][datetime] DEFAULT(GETDATE()) NOT NULL, [IsActive][bit] DEFAULT(1) NOT NULL )CREATE TABLE [dbo].[CICRole] ( [RoleId][int] IDENTITY(1, 1) PRIMARY KEY NOT NULL, [RoleName][nvarchar](256) NOT NULL, )CREATE TABLE [dbo].[CICUserRole] ( [Id][int] IDENTITY(1, 1) PRIMARY KEY NOT NULL, [UserId][int] FOREIGN KEY REFERENCES [dbo].[CICUser] ([UserId]) NOT NULL, [RoleId][int] FOREIGN KEY REFERENCES [dbo].[CICRole] ([RoleId]) NOT NULL )

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2.2实体类。
在创建实体类时，属性名称一定要与数据库字段一一对应。

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public class User { public User() { Role = new List< Role> (); } public int UserId { get; set; } public string UserName { get; set; } public string Password { get; set; } public string Email { get; set; } public string PhoneNumber { get; set; } public bool IsFirstTimeLogin { get; set; } public int AccessFailedCount { get; set; } public DateTime CreationDate { get; set; } public bool IsActive { get; set; } public List< Role> Role { get; set; } } public class Role { public int RoleId { get; set; } public string RoleName { get; set; } } public class Customer { public int UserId { get; set; } public string UserName { get; set; } public string Password { get; set; } public string Email { get; set; } public string PhoneNumber { get; set; } public bool IsFirstTimeLogin { get; set; } public int AccessFailedCount { get; set; } public DateTime CreationDate { get; set; } public bool IsActive { get; set; } public Role Role { get; set; } }

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3.使用方法
3.1 一对一映射

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private static void OneToOne(string sqlConnectionString) { List< Customer> userList = new List< Customer> (); using (IDbConnection conn = GetSqlConnection(sqlConnectionString)) { string sqlCommandText = @"SELECT c.UserId,c.Username AS UserName, c.PasswordHash AS [Password],c.Email,c.PhoneNumber,c.IsFirstTimeLogin,c.AccessFailedCount, c.CreationDate,c.IsActive,r.RoleId,r.RoleName FROM dbo.CICUser c WITH(NOLOCK) INNER JOIN CICUserRole cr ON cr.UserId = c.UserId INNER JOIN CICRole r ON r.RoleId = cr.RoleId"; userList = conn.Query< Customer, Role, Customer> (sqlCommandText, (user, role) => { user.Role = role; return user; }, null, null, true, "RoleId", null, null).ToList(); }if (userList.Count > 0) { userList.ForEach((item) => Console.WriteLine("UserName:" + item.UserName + "----Password:" + item.Password + "-----Role:" + item.Role.RoleName + "\n")); Console.ReadLine(); } }

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3.2 一对多映射

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private static void OneToMany(string sqlConnectionString) { Console.WriteLine("One To Many"); List< User> userList = new List< User> (); using (IDbConnection connection = GetSqlConnection(sqlConnectionString)) {string sqlCommandText3 = @"SELECT c.UserId, c.UsernameAS UserName, c.PasswordHashAS [Password], c.Email, c.PhoneNumber, c.IsFirstTimeLogin, c.AccessFailedCount, c.CreationDate, c.IsActive, r.RoleId, r.RoleName FROMdbo.CICUser c WITH(NOLOCK) LEFT JOIN CICUserRole cr ONcr.UserId = c.UserId LEFT JOIN CICRole r ONr.RoleId = cr.RoleId"; var lookUp = new Dictionary< int, User> (); userList = connection.Query< User, Role, User> (sqlCommandText3, (user, role) => { User u; if (!lookUp.TryGetValue(user.UserId, out u)) { lookUp.Add(user.UserId, u = user); } u.Role.Add(role); return user; }, null, null, true, "RoleId", null, null).ToList(); var result = lookUp.Values; }if (userList.Count > 0) { userList.ForEach((item) => Console.WriteLine("UserName:" + item.UserName + "----Password:" + item.Password + "-----Role:" + item.Role.First().RoleName + "\n")); Console.ReadLine(); } else { Console.WriteLine("No Data In UserList!"); } }

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3.3 插入实体

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public static void InsertObject(string sqlConnectionString) { string sqlCommandText = @"INSERT INTO CICUser(Username,PasswordHash,Email,PhoneNumber)VALUES( @UserName, @Password, @Email, @PhoneNumber )"; using (IDbConnection conn = GetSqlConnection(sqlConnectionString)) { User user = new User(); user.UserName = "Dapper"; user.Password = "654321"; user.Email = "[email protected]"; user.PhoneNumber = "13795666243"; int result = conn.Execute(sqlCommandText, user); if (result > 0) { Console.WriteLine("Data have already inserted into DB!"); } else { Console.WriteLine("Insert Failed!"); }Console.ReadLine(); } }

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3.4 执行存储过程

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/// < summary> /// Execute StoredProcedure and map result to POCO /// < /summary> /// < param name="sqlConnnectionString"> < /param> public static void ExecuteStoredProcedure(string sqlConnnectionString) { List< User> users = new List< User> (); using (IDbConnection cnn = GetSqlConnection(sqlConnnectionString)) { users = cnn.Query< User> ("dbo.p_getUsers", new { UserId = 2 }, null, true, null, CommandType.StoredProcedure).ToList(); } if (users.Count > 0) { users.ForEach((user) => Console.WriteLine(user.UserName + "\n")); } Console.ReadLine(); }

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