Dapper.NET—轻量ORM

Dapper.NET使用

本文目录

• Dapper.NET使用
• 1、为什么选择Dapper
• 2、以Dapper（4.0）为例。
• 2.1 在数据库中建立几张表。
• 2.2实体类。
• 3.使用方法
• 3.1  一对一映射
• 3.2 一对多映射
• 3.3 插入实体
• 3.4 执行存储过程

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。

访问量不大的项目可以考虑用EF写数据库操作，因为EF除了速度上慢以外，但开发效率极快，省略了很多sql写法，并能很方便的调用外键、集合等信息，用EF写项目最爽的事。

不过有些项目网站要考虑运行速度，这时不得不用其它的ORM框架，比如用Dapper，因为它速度快，而且写sql非常灵活。

1、为什么选择Dapper

1. 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)
2. 速度快。Dapper的速度接近与IDataReader，取列表的数据超过了DataTable。
3. 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
4. 可以映射一对一，一对多，多对多等多种关系。
5. 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。
6. 支持FrameWork2.0，3.0，3.5，4.0，4.5
7. Dapper语法十分简单。并且无须迁就数据库的设计

2、以Dapper（4.0）为例

先通过NuGet进行安装Dapper

PM> Install-Package Dapper -Version 1.40.

2.1 在数据库中建立几张表

CREATE TABLE [dbo].[CICUser]
(
    [UserId]                [int] IDENTITY(, ) PRIMARY KEY NOT NULL,
    [Username]              [nvarchar]() NOT NULL,
    [PasswordHash]          [nvarchar]() NULL,
    [Email]                 [nvarchar]() NULL,
    [PhoneNumber]           [nvarchar]() NULL,
    [IsFirstTimeLogin]      [bit] DEFAULT() NOT NULL,
    [AccessFailedCount]     [int] DEFAULT() NOT NULL,
    [CreationDate]          [datetime] DEFAULT(GETDATE()) NOT NULL,
    [IsActive]              [bit] DEFAULT() NOT NULL
)

CREATE TABLE [dbo].[CICRole]
(
    [RoleId]       [int] IDENTITY(, ) PRIMARY KEY NOT NULL,
    [RoleName]     [nvarchar]() NOT NULL,
)

CREATE TABLE [dbo].[CICUserRole]
(
     [Id]   [int] IDENTITY(, ) 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 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; }
}    

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 > )
            {
                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 > )
            {
                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 = "";
                user.Email = "Dapper@infosys.com";
                user.PhoneNumber = "";
                int result = conn.Execute(sqlCommandText, user);
                if (result > )
                {
                    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 =  },
                                        null,
                                        true,
                                        null,
                                        CommandType.StoredProcedure).ToList();
            }
            if (users.Count > )
            {
                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", "");
            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();
        }