Dapper.NET——輕量ORM

Dapper.NET使用

Dapper是一款輕量級ORM工具（Github）。如果你在小的項目中，使用Entity Framework、NHibernate 來處理大數據訪問及關系映射，未免有點殺雞用牛刀。你又覺得ORM省時省力，這時Dapper 將是你不二的選擇。

1、為什么選擇Dapper

1. 輕量。只有一個文件（SqlMapper.cs），編譯完成之后只有120k(好象是變胖了)
2. 速度快。Dapper的速度接近與IDataReader，取列表的數據超過了DataTable。
3. 支持多種數據庫。Dapper可以在所有Ado.net Providers下工作，包括sqlite, sqlce, firebird, oracle, MySQL, PostgreSQL and SQL Server
4. 可以映射一對一，一對多，多對多等多種關系。
5. 性能高。通過Emit反射IDataReader的序列隊列，來快速的得到和產生對象，性能不錯。
6. 支持FrameWork2.0，3.0，3.5，4.0，4.5

2、以Dapper（4.0）為例。

2.1 在數據庫中建立幾張表。

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
)

2.2實體類。

在創建實體類時，屬性名稱一定要與數據庫字段一一對應。

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; }
    }    

3.使用方法

3.1  一對一映射

 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 一對多映射

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 插入實體

 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 = "[e-mail]";
                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 執行存儲過程

         /// <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();
        }