Dapper.NET——轻量ORM

Posted 2020-06-24 SherlockHolmes

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

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

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; }
}

 

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

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 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();
}
 
使用示例代码
string connString=ConfigurationManager.ConnectionStrings["mall"].ConnectionString;
 
//执行查询
using (MySqlConnection conn = new MySqlConnection(connString))
{
var books = conn.Query<Book>("select Title,Author from Book where Author=@Author", new { Author = "Ben" });
foreach (var item in books)
{
Console.WriteLine(item.Title + item.Author);
}
Console.ReadKey();
}
 
//执行存储过程(带参)
using (MySqlConnection conn = new MySqlConnection(connString))
{
var books = conn.Query<Book>("Prc_book", new { Auth = "Ben" }, null, true, null, CommandType.StoredProcedure);
foreach (var item in books)
{
Console.WriteLine(item.Title + item.Author);
}
Console.ReadKey();
}
 
//执行连接查询
using (MySqlConnection conn = new MySqlConnection(connString))
{
var results = conn.Query(@"SELECT*FROM book AS a INNER JOIN category AS b ON a.Id=b.Id");
foreach (var item in results)
{
Console.WriteLine(item.Title + item.Author);
}
Console.ReadKey();
}
 
//插入单行数据
using (MySqlConnection conn = new MySqlConnection(connString))
{
var results = conn.Execute(@"INSERT INTO category VALUES(null,@name,@parentid)", new Category { Name = @"数据", ParentId = 003 });
Console.WriteLine(results);
Console.ReadKey();
}
 
//插入多行数据
var list = new List<Category>();
for (int i = 0; i < 200; i++)
{
list.Add(new Category { Name = @"Shopping", ParentId = 003 });
}
using (MySqlConnection conn = new MySqlConnection(connString))
{
var results = conn.Execute(@"INSERT INTO category VALUES(null,@name,@parentid)", list);
Console.WriteLine(results);
Console.ReadKey();
}
 
//多个查询
using (MySqlConnection conn = new MySqlConnection(connString))
{
var results = conn.QueryMultiple(@"select*from book where Author=@Author;select*from category where Name=@Name", new{Author="Ben",Name="JAVA"});
var books=results.Read<Book>();
foreach (var item in books)
{
Console.WriteLine(item.Title);
}
 
var category = results.Read<Category>();
foreach (var item in category)
{
Console.WriteLine(item.Id);
}
Console.ReadKey();
}