ASP.NET Core 中的 ORM 之 Dapper

阿新 • • 發佈：2019-02-07

Dapper簡介

Dapper是.NET的一款輕量級ORM工具（GitHub），也可稱為簡單物件對映器。在速度方面擁有微型ORM之王的稱號。
它是半自動的，也就是說實體類和SQL語句都要自己寫，但它提供自動物件對映。是通過對IDbConnection介面的擴充套件來操作資料庫的。

優點：

輕量，只有一個檔案
效能高，Dapper的速度接近與IDataReader，取列表的資料超過了DataTable。
支援多種資料庫。Dapper可以在所有Ado.net Providers下工作，包括sqlite, sqlce, firebird, oracle, MySQL, PostgreSQL and SQL Server

使用Dapper可以自動進行物件對映，通過Emit反射IDataReader的序列佇列，來快速的得到和產生物件

使用Dapper

下面簡單建立一個Web API應用並通過Dapper訪問MySQL資料。

建立MySQL測試資料

CREATE SCHEMA `ormdemo` ;

CREATE TABLE `ormdemo`.`category` (
  `Id` INT NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(45) NOT NULL,
  PRIMARY KEY (`Id`));

CREATE TABLE `ormdemo`.`product` (
  `Id` INT NOT NULL AUTO_INCREMENT,
  `Name` VARCHAR(45) NOT NULL,
  `Price` DECIMAL(19,2) NULL,
  `Quantity` INT NULL,
  `CategoryId` INT NOT NULL,
  PRIMARY KEY (`Id`),
  INDEX `fk_product_category_idx` (`CategoryId` ASC),
  CONSTRAINT `fk_product_category`
    FOREIGN KEY (`CategoryId`)
    REFERENCES `ormdemo`.`category` (`Id`)
    ON DELETE CASCADE
    ON UPDATE NO ACTION);  

INSERT INTO `ormdemo`.`category` (`Name`) VALUES("Phones");
INSERT INTO `ormdemo`.`category` (`Name`) VALUES("Computers");

INSERT INTO `ormdemo`.`product` (`Name`,`Price`,`Quantity`,`CategoryId`) VALUES("iPhone8",4999.99,10,1);
INSERT INTO `ormdemo`.`product` (`Name`,`Price`,`Quantity`,`CategoryId`) VALUES("iPhone7",2999.99,10,1);
INSERT INTO `ormdemo`.`product` (`Name`,`Price`,`Quantity`,`CategoryId`) VALUES("HP750",6000.00,5,2);
INSERT INTO `ormdemo`.`product` (`Name`,`Price`,`Quantity`,`CategoryId`) VALUES("HP5000",12000.00,10,2);

建立Web API應用並新增NuGet引用

Install-Package MySql.Data
Install-Package Dapper

新建一個Product類

public class Category
{
    public int Id { get; set; }

    public string Name { get; set; }
}

public class Product
{
    public int Id { get; set; }

    public string Name { get; set; }

    public int Quantity { get; set; }

    public decimal Price { get; set; }

    public int CategoryId { get; set; }

    public virtual Category Category { get; set; }
}

新建一個DBConfig類用於建立並返回資料庫連線

using MySql.Data.MySqlClient;
using System.Data;
using System.Configuration;

public class DBConfig
{
    //ConfigurationManager.ConnectionStrings["Connection"].ConnectionString;
    private static string DefaultSqlConnectionString = @"server=127.0.0.1;database=ormdemo;uid=root;pwd=Open0001;SslMode=none;";

    public static IDbConnection GetSqlConnection(string sqlConnectionString = null)
    {
        if (string.IsNullOrWhiteSpace(sqlConnectionString))
        {
            sqlConnectionString = DefaultSqlConnectionString;
        }
        IDbConnection conn = new MySqlConnection(sqlConnectionString);
        conn.Open();
        return conn;
    }
}

建立簡單的倉儲介面和類

public interface IProductRepository
{
    Task<bool> AddAsync(Product prod);
    Task<IEnumerable<Product>> GetAllAsync();
    Task<Product> GetByIDAsync(int id);
    Task<bool> DeleteAsync(int id);
    Task<bool> UpdateAsync(Product prod);
}

public class ProductRepository : IProductRepository
{
    public async Task<IEnumerable<Product>> GetAllAsync()
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            return await conn.QueryAsync<Product>(@"SELECT Id
                                            ,Name
                                            ,Quantity
                                            ,Price
                                            ,CategoryId
                                        FROM Product");
        }
    }

    public async Task<Product> GetByIDAsync(int id)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            string sql = @"SELECT Id
                                ,Name
                                ,Quantity
                                ,Price 
                                ,CategoryId
                            FROM Product
                            WHERE Id = @Id";
            return await conn.QueryFirstOrDefaultAsync<Product>(sql, new { Id = id });
        }
    }

    public async Task<bool> AddAsync(Product prod)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            string sql = @"INSERT INTO Product 
                            (Name
                            ,Quantity
                            ,Price
                            ,CategoryId)
                        VALUES
                            (@Name
                            ,@Quantity
                            ,@Price
                            ,@CategoryId)";
            return await conn.ExecuteAsync(sql, prod) > 0;
        }
    }

    public async Task<bool> UpdateAsync(Product prod)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            string sql = @"UPDATE Product SET 
                                Name = @Name
                                ,Quantity = @Quantity
                                ,Price= @Price
                                ,CategoryId= @CategoryId
                           WHERE Id = @Id";
            return await conn.ExecuteAsync(sql, prod) > 0;
        }
    }

    public async Task<bool> DeleteAsync(int id)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            string sql = @"DELETE FROM Product
                            WHERE Id = @Id";
            return await conn.ExecuteAsync(sql, new { Id = id }) > 0;
        }
    }
}

在Startup ConfigureServices方法裡面配置依賴注入

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<IProductRepository, ProductRepository>();

    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}

在Controller裡面呼叫倉儲方法

[Route("api/[controller]")]
[ApiController]
public class ProductController : ControllerBase
{
    private readonly IProductRepository _productRepository;
    public ProductController(IProductRepository productRepository)
    {
        _productRepository = productRepository;
    }

    [HttpGet]
    public async Task<IActionResult> Get()
    {
        var data = await _productRepository.GetAllAsync();
        return Ok(data);
    }

    [HttpGet("{id}")]
    public async Task<IActionResult> Get(int id)
    {
        var data = await _productRepository.GetByIDAsync(id);
        return Ok(data);
    }

    [HttpPost]
    public async Task<IActionResult> Post([FromBody] Product prod)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        await _productRepository.AddAsync(prod);
        return NoContent();
    }

    [HttpPut("{id}")]
    public async Task<IActionResult> Put(int id, [FromBody] Product prod)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        var model = await _productRepository.GetByIDAsync(id);
        model.Name = prod.Name;
        model.Quantity = prod.Quantity;
        model.Price = prod.Price;
        await _productRepository.UpdateAsync(model);

        return NoContent();
    }

    [HttpDelete("{id}")]
    public async Task<IActionResult> Delete(int id)
    {
        await _productRepository.DeleteAsync(id);
        return NoContent();
    }
}

測試API是否可以正常工作

Dapper對儲存過程和事務的支援

儲存過程

using (var connection = My.ConnectionFactory())
{
    connection.Open();

    var affectedRows = connection.Execute(sql,
        new {Kind = InvoiceKind.WebInvoice, Code = "Single_Insert_1"},
        commandType: CommandType.StoredProcedure);

    My.Result.Show(affectedRows);
}

事務

using (var connection = My.ConnectionFactory())
{
    connection.Open();

    using (var transaction = connection.BeginTransaction())
    {
        var affectedRows = connection.Execute(sql, new {CustomerName = "Mark"}, transaction: transaction);

        transaction.Commit();
    }
}

Dapper對多表對映的支援

var selectAllProductWithCategorySQL = @"select * from product p 
    inner join category c on c.Id = p.CategoryId
    Order by p.Id";
var allProductWithCategory = connection.Query<Product, Category, Product>(selectAllProductWithCategorySQL, (prod, cg) => { prod.Category = cg; return prod; });

使用Dapper Contrib或其他擴充套件

Dapper Contrib擴充套件Dapper提供了CRUD的方法

Get
GetAll
Insert
Update
Delete
DeleteAll

新增NuGet引用Dapper.Contrib
```
Install-Package Dapper.Contrib
```

為Product類新增資料註解

[Table("Product")]
public class Product
{
    [Key]
    public int Id { get; set; }

    public string Name { get; set; }

    public int Quantity { get; set; }

    public decimal Price { get; set; }

    public int CategoryId { get; set; }

    public virtual Category Category { get; set; }
}

增加一個新的倉儲類繼承

public class ContribProductRepository : IProductRepository
{
    public async Task<bool> AddAsync(Product prod)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            return await conn.InsertAsync(prod) > 0;
        }
    }

    public async Task<IEnumerable<Product>> GetAllAsync()
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            return await conn.GetAllAsync<Product>();
        }
    }

    public async Task<Product> GetByIDAsync(int id)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            return await conn.GetAsync<Product>(id);
        }
    }

    public async Task<bool> DeleteAsync(int id)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            var entity = await conn.GetAsync<Product>(id);
            return await conn.DeleteAsync(entity);
        }
    }

    public async Task<bool> UpdateAsync(Product prod)
    {
        using (IDbConnection conn = DBConfig.GetSqlConnection())
        {
            return await conn.UpdateAsync(prod);
        }
    }
}

修改Startup ConfigureServices方法裡面配置依賴注入

services.AddTransient<IProductRepository, ContribProductRepository>();

測試，這樣可以少寫了不少基本的SQL語句。

其他一些開源的Dapper擴充套件

類庫	提供的方法
`Get` `GetList` `GetListPaged` `Insert` `Update` `Delete` `DeleteList` `RecordCount`
`Bulk Insert` `Bulk Delete` `Bulk Update` `Bulk Merge` `Bulk Action Async` `Bulk Also Action` `Bulk Then Action`
`Get` `Find` `Insert` `Update` `BulkUpdate` `Delete` `BulkDelete` `Count`

引入工作單元Unit of Work

倉儲模式往往需要工作單元模式的介入來負責一系列倉儲物件的持久化，確保資料完整性。網上關於工作單元模式的實現方式有多種，但其本質都是工作單元類通過建立一個所有倉儲共享的資料庫上下文物件，來組織多個倉儲物件。

網上的一些實現方式：

public class UnitOfWork : IDisposable
{
    private SchoolContext context = new SchoolContext();
    private GenericRepository<Department> departmentRepository;
    private GenericRepository<Course> courseRepository;

    public GenericRepository<Department> DepartmentRepository
    {
        get
        {

            if (this.departmentRepository == null)
            {
                this.departmentRepository = new GenericRepository<Department>(context);
            }
            return departmentRepository;
        }
    }

    public GenericRepository<Course> CourseRepository
    {
        get
        {

            if (this.courseRepository == null)
            {
                this.courseRepository = new GenericRepository<Course>(context);
            }
            return courseRepository;
        }
    }

    public void Save()
    {
        context.SaveChanges();
    }

    private bool disposed = false;

    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposed)
        {
            if (disposing)
            {
                context.Dispose();
            }
        }
        this.disposed = true;
    }

    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }
}

優缺點不作討論，適合自己的就是最好的，這裡採用了另外一種實現方式：

定義DapperDBContext

public interface IContext : IDisposable
{
    bool IsTransactionStarted { get; }

    void BeginTransaction();

    void Commit();

    void Rollback();
}

public abstract class DapperDBContext : IContext
{
    private IDbConnection _connection;
    private IDbTransaction _transaction;
    private int? _commandTimeout = null;
    private readonly DapperDBContextOptions _options;

    public bool IsTransactionStarted { get; private set; }

    protected abstract IDbConnection CreateConnection(string connectionString);

    protected DapperDBContext(IOptions<DapperDBContextOptions> optionsAccessor)
    {
        _options = optionsAccessor.Value;

        _connection = CreateConnection(_options.Configuration);
        _connection.Open();

        DebugPrint("Connection started.");
    }

    #region Transaction

    public void BeginTransaction()
    {
        if (IsTransactionStarted)
            throw new InvalidOperationException("Transaction is already started.");

        _transaction = _connection.BeginTransaction();
        IsTransactionStarted = true;

        DebugPrint("Transaction started.");
    }

    public void Commit()
    {
        if (!IsTransactionStarted)
            throw new InvalidOperationException("No transaction started.");

        _transaction.Commit();
        _transaction = null;

        IsTransactionStarted = false;

        DebugPrint("Transaction committed.");
    }

    public void Rollback()
    {
        if (!IsTransactionStarted)
            throw new InvalidOperationException("No transaction started.");

        _transaction.Rollback();
        _transaction.Dispose();
        _transaction = null;

        IsTransactionStarted = false;

        DebugPrint("Transaction rollbacked and disposed.");
    }

    #endregion Transaction

    #region Dapper Execute & Query

    public async Task<int> ExecuteAsync(string sql, object param = null, CommandType commandType = CommandType.Text)
    {
        return await _connection.ExecuteAsync(sql, param, _transaction, _commandTimeout, commandType);
    }

    public async Task<IEnumerable<T>> QueryAsync<T>(string sql, object param = null, CommandType commandType = CommandType.Text)
    {
        return await _connection.QueryAsync<T>(sql, param, _transaction, _commandTimeout, commandType);
    }

    public async Task<T> QueryFirstOrDefaultAsync<T>(string sql, object param = null, CommandType commandType = CommandType.Text)
    {
        return await _connection.QueryFirstOrDefaultAsync<T>(sql, param, _transaction, _commandTimeout, commandType);
    }

    public async Task<IEnumerable<TReturn>> QueryAsync<TFirst, TSecond, TReturn>(string sql, Func<TFirst, TSecond, TReturn> map, object param = null, string splitOn = "Id", CommandType commandType = CommandType.Text)
    {
        return await _connection.QueryAsync(sql, map, param, _transaction, true, splitOn, _commandTimeout, commandType);
    }

    #endregion Dapper Execute & Query

    public void Dispose()
    {
        if (IsTransactionStarted)
            Rollback();

        _connection.Close();
        _connection.Dispose();
        _connection = null;

        DebugPrint("Connection closed and disposed.");
    }

    private void DebugPrint(string message)
    {
#if DEBUG
        Debug.Print(">>> UnitOfWorkWithDapper - Thread {0}: {1}", Thread.CurrentThread.ManagedThreadId, message);
#endif
    }
}

定義UnitOfWork

public interface IUnitOfWork : IDisposable
{
    void SaveChanges();
}

public class UnitOfWork : IUnitOfWork
{
    private readonly IContext _context;

    public UnitOfWork(IContext context)
    {
        _context = context;
        _context.BeginTransaction();
    }

    public void SaveChanges()
    {
        if (!_context.IsTransactionStarted)
            throw new InvalidOperationException("Transaction have already been commited or disposed.");

        _context.Commit();
    }

    public void Dispose()
    {
        if (_context.IsTransactionStarted)
            _context.Rollback();
    }
}

定義UnitOfWorkFactory

public interface IUnitOfWorkFactory
{
    IUnitOfWork Create();
}

public class DapperUnitOfWorkFactory : IUnitOfWorkFactory
{
    private readonly DapperDBContext _context;

    public DapperUnitOfWorkFactory(DapperDBContext context)
    {
        _context = context;
    }

    public IUnitOfWork Create()
    {
        return new UnitOfWork(_context);
    }
}

定義服務擴充套件

public class DapperDBContextOptions : IOptions<DapperDBContextOptions>
{
    public string Configuration { get; set; }

    DapperDBContextOptions IOptions<DapperDBContextOptions>.Value
    {
        get { return this; }
    }
}

public static class DapperDBContextServiceCollectionExtensions
{
    public static IServiceCollection AddDapperDBContext<T>(this IServiceCollection services, Action<DapperDBContextOptions> setupAction) where T : DapperDBContext
    {
        if (services == null)
        {
            throw new ArgumentNullException(nameof(services));
        }

        if (setupAction == null)
        {
            throw new ArgumentNullException(nameof(setupAction));
        }

        services.AddOptions();
        services.Configure(setupAction);
        services.AddScoped<DapperDBContext, T>();
        services.AddScoped<IUnitOfWorkFactory, DapperUnitOfWorkFactory>();

        return services;
    }
}

怎麼使用

建立一個自己的Context並繼承DapperDBContext。下面測試的TestDBContext是採用MySQL資料庫並返回MySqlConnection。

public class TestDBContext : DapperDBContext
{
    public TestDBContext(IOptions<DapperDBContextOptions> optionsAccessor) : base(optionsAccessor)
    {
    }

    protected override IDbConnection CreateConnection(string connectionString)
    {
        IDbConnection conn = new MySqlConnection(connectionString);
        return conn;
    }
}

倉儲類裡面新增DapperDBContext引用

public class UowProductRepository : IProductRepository
{
    private readonly DapperDBContext _context;
    public UowProductRepository(DapperDBContext context)
    {
        _context = context;
    }


    public async Task<Product> GetByIDAsync(int id)
    {
        string sql = @"SELECT Id
                            ,Name
                            ,Quantity
                            ,Price 
                            ,CategoryId
                        FROM Product
                        WHERE Id = @Id";
        return await _context.QueryFirstOrDefaultAsync<Product>(sql, new { Id = id });
    }

    public async Task<bool> AddAsync(Product prod)
    {
        string sql = @"INSERT INTO Product 
                        (Name
                        ,Quantity
                        ,Price
                        ,CategoryId)
                    VALUES
                        (@Name
                        ,@Quantity
                        ,@Price
                        ,@CategoryId)";
        return await _context.ExecuteAsync(sql, prod) > 0;
    }
}

Startup裡面註冊服務

public void ConfigureServices(IServiceCollection services)
{
    services.AddDapperDBContext<TestDBContext>(options => {
        options.Configuration = @"server=127.0.0.1;database=ormdemo;uid=root;pwd=password;SslMode=none;";
    });

    services.AddTransient<IProductRepository, UowProductRepository>();
    services.AddTransient<ICategoryRepository, UowCategoryRepository>();

    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}

Controller呼叫

public class ProductController : ControllerBase
{
    private readonly IUnitOfWorkFactory _uowFactory;
    private readonly IProductRepository _productRepository;
    private readonly ICategoryRepository _categoryRepository;

    public ProductController(IUnitOfWorkFactory uowFactory, IProductRepository productRepository, ICategoryRepository categoryRepository)
    {
        _uowFactory = uowFactory;
        _productRepository = productRepository;
        _categoryRepository = categoryRepository;
    }

    [HttpGet("{id}")]
    public async Task<IActionResult> Get(int id)
    {
        var data = await _productRepository.GetByIDAsync(id);
        return Ok(data);
    }

    [HttpPost]
    public async Task<IActionResult> Post([FromBody] Product prod)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        //await _productRepository.AddAsync(prod);

        using (var uow = _uowFactory.Create())
        {
            await _productRepository.AddAsync(prod);

            uow.SaveChanges();
        }

        return NoContent();
    }
}

ASP.NET Core 中的 ORM 之 Dapper

Dapper簡介

使用Dapper

使用Dapper Contrib或其他擴充套件

引入工作單元Unit of Work

原始碼

參考

ASP.NET Core 中的 ORM 之 Dapper

ASP.NET Core 中的 ORM 之 Entity Framework

ASP.NET Core 中的物件對映之 AutoMapper

在Asp.Net Core中集成ABP Dapper

Asp.Net Core 中IdentityServer4 授權中心之應用實戰

Asp.Net Core 中IdentityServer4 授權中心之自定義授權模式

Asp.Net Core 中IdentityServer4 實戰之角色授權詳解

Asp.Net Core中Json序列化處理整理

asp.net core中負載均衡場景下http重定向https的問題

體驗 ASP.NET Core 中的多語言支持（Localization）

在ASP.NET Core 中使用Cookie中間件

ASP.NET.Core中使用AutoMapper

IdentityServer4在Asp.Net Core中的應用(一)

IdentityServer4在Asp.Net Core中的應用(二)

asp.net core中遇到需要自定義數據包解密方法的時候

ASP.NET Core中使用Razor視圖引擎渲染視圖為字符串(轉)

asp.net core中IHttpContextAccessor和HttpContextAccessor的妙用

Asp.Net Core中利用Seq組件展示結構化日誌功能

Asp.Net Core中使用Swagger，你不得不踩的坑

在Asp.Net Core中使用中間件保護非公開文件

ASP.NET Core 中的 ORM 之 Dapper

Dapper簡介

使用Dapper

使用Dapper Contrib或其他擴充套件

引入工作單元Unit of Work

原始碼

參考

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