Dapper.NET——轻量ORM

浏览数：39 / 时间：2015年06月11日

Dapper.NET使用

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。

1.在数据库中建立几张表。

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
)

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。

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; }
    }

实体类

3.使用方法

3.1 一对一映射

 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();
            }
        }

3.2 一对多映射

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.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)
       LEFT JOIN CICUserRole cr
            ON  cr.UserId = c.UserId
       LEFT JOIN CICRole r
            ON  r.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!");
            }
        }

3.3 插入实体

 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();
            }
        }

3.4 执行存储过程

         /// <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();
        }

        /// <summary>
        /// Execute StroedProcedure and get result from return value
        /// </summary>
        /// <param name="sqlConnnectionString"></param>
        public static void ExecuteStoredProcedureWithParms(string sqlConnnectionString)
        {
            DynamicParameters p = new DynamicParameters();
            p.Add("@UserName", "cooper");
            p.Add("@Password", "123456");
            p.Add("@LoginActionType", null, DbType.Int32, ParameterDirection.ReturnValue);
            using (IDbConnection cnn = GetSqlConnection(sqlConnnectionString))
            {
                cnn.Execute("dbo.p_validateUser", p, null, null, CommandType.StoredProcedure);
                int result = p.Get<int>("@LoginActionType");
                Console.WriteLine(result);
            }

            Console.ReadLine();
        }