Dapper.NET——轻量ORM
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。
2.1 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 )
2.2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 > 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 = "Dapper@infosys.com"; 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(); }
