6

根据我的理解，我整理了一个示例，说明我如何使用工作单元和存储库模式。如果我以正确的方式实施，谁能告诉我？如果我不是，我该如何改进它？

在此先感谢，非常感谢。

我有一个包含两个实体的 EF 模型：主题和子主题。EF 模型称为 CommonGood。

工作单位：

/// <summary>
/// Implementation of a UnitOfWork class
/// </summary>
public static class UnitOfWork
{
    /// <summary>
    /// Gets the default context
    /// </summary>
    /// <returns>A new instance of the default context</returns>
    public static CommonGoodEntities GetContext()
    {
        return new CommonGoodEntities();
    }
}

IGenericRepository：

public interface IRepository<T>
{
    /// <summary>
    /// Gets all entities
    /// </summary>        
    /// <returns>All entities</returns>
    IEnumerable<T> GetAll();

    /// <summary>
    /// Gets all entities matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>All entities matching the predicate</returns>
    IEnumerable<T> GetAll(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Set based on where condition
    /// </summary>
    /// <param name="predicate">The predicate</param>
    /// <returns>The records matching the given condition</returns>
    IQueryable<T> Where(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Finds an entity matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate</returns>
    IEnumerable<T> Find(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Determines if there are any entities matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>True if a match was found</returns>
    bool Any(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Returns the first entity that matches the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate</returns>
    T First(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Returns the first entity that matches the predicate else null
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate else null</returns>
    T FirstOrDefault(Expression<Func<T, bool>> predicate);

    /// <summary>
    /// Adds a given entity to the context
    /// </summary>
    /// <param name="entity">The entity to add to the context</param>
    void Add(T entity);

    /// <summary>
    /// Deletes a given entity from the context
    /// </summary>
    /// <param name="entity">The entity to delete</param>
    void Delete(T entity);

    /// <summary>
    /// Attaches a given entity to the context
    /// </summary>
    /// <param name="entity">The entity to attach</param>
    void Attach(T entity);
}

通用存储库：

public class GenericRepository<T> : IRepository<T> where T : class
{
    /// <summary>
    /// The database context for the repository
    /// </summary>
    private DbContext _context;

    /// <summary>
    /// The data set of the repository
    /// </summary>
    private IDbSet<T> _dbSet;

    /// <summary>
    /// Initializes a new instance of the <see cref="GenericRepository{T}" /> class.        
    /// </summary>
    /// <param name="context">The context for the repository</param>        
    public GenericRepository(DbContext context)
    {
        this._context = context;
        this._dbSet = this._context.Set<T>();
    }

    /// <summary>
    /// Gets all entities
    /// </summary>        
    /// <returns>All entities</returns>
    public IEnumerable<T> GetAll()
    {
        return this._dbSet;
    }

    /// <summary>
    /// Gets all entities matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>All entities matching the predicate</returns>
    public IEnumerable<T> GetAll(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.Where(predicate);
    }

    /// <summary>
    /// Set based on where condition
    /// </summary>
    /// <param name="predicate">The predicate</param>
    /// <returns>The records matching the given condition</returns>
    public IQueryable<T> Where(Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.Where(predicate);
    }

    /// <summary>
    /// Finds an entity matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate</returns>
    public IEnumerable<T> Find(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.Where(predicate);
    }

    /// <summary>
    /// Determines if there are any entities matching the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>True if a match was found</returns>
    public bool Any(Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.Any(predicate);
    }

    /// <summary>
    /// Returns the first entity that matches the predicate
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate</returns>
    public T First(Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.First(predicate);
    }

    /// <summary>
    /// Returns the first entity that matches the predicate else null
    /// </summary>
    /// <param name="predicate">The filter clause</param>
    /// <returns>An entity matching the predicate else null</returns>
    public T FirstOrDefault(Expression<Func<T, bool>> predicate)
    {
        return this._dbSet.FirstOrDefault(predicate);
    }

    /// <summary>
    /// Adds a given entity to the context
    /// </summary>
    /// <param name="entity">The entity to add to the context</param>
    public void Add(T entity)
    {
        this._dbSet.Add(entity);
    }

    /// <summary>
    /// Deletes a given entity from the context
    /// </summary>
    /// <param name="entity">The entity to delete</param>
    public void Delete(T entity)
    {
        this._dbSet.Remove(entity);
    }

    /// <summary>
    /// Attaches a given entity to the context
    /// </summary>
    /// <param name="entity">The entity to attach</param>
    public void Attach(T entity)
    {
        this._dbSet.Attach(entity);
    }
}

控制器：

public class HomeController : Controller
{
    /// <summary>
    /// The context used for the controller
    /// </summary>
    private DbContext _context;

    /// <summary>
    /// Initializes a new instance of the <see cref="HomeController"/> class.
    /// </summary>        
    public HomeController()
    {
        this._context = UnitOfWork.GetContext();
    }

    public JsonResult GetTopics()
    {
        var topics = new GenericRepository<Topic>(this._context).GetAll().ToList();            
        return this.Json(topics, JsonRequestBehavior.AllowGet);
    }

    /// <summary>
    /// Disposes of the context if the currently disposing
    /// </summary>
    /// <param name="disposing">A value indicating whether or not the application is disposing</param>
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            this._context.Dispose();
        }

        base.Dispose(disposing);
    }
}

本质上，我想确保我以正确的方式访问数据并确保我没有忽略任何东西。再次，谢谢！

4

1 回答 1

8

将 UnitOfWork 实现为静态类并不完美。定义一个接口 IUnitOfWork。您的数据库上下文将实现此接口。它可能看起来像：

public interface IUnitOfWork {
    int SaveChanges();
}

public class EFDbContext: DbContext, IUnitOfWork {

    public DbSet<User> User { get; set; }

    public EFDbContext(string connectionString)
        : base(connectionString) { }

    public override int SaveChanges() {
        return base.SaveChanges();
    }
}

我通常创建几个从通用存储库继承的存储库。因此存储库查找方法的名称可以具有更具体的名称。这也防止了不同控制器中存储库逻辑的重复。

例如：

    public class EFUserRepository: EFRepository<User>, IUserRepository {

    public EFUserRepository(IUnitOfWork context)
        : base(context) { }

    protected override DbSet<User> Table {
        get { return Context.User; }
    }

    public User Find(string email) {
        return Table.FirstOrDefault(u => u.Email == email);
    }

    public bool Validate(string email, string password) {
        string passwordHash = Cryptography.GenerateHash(password);
        User user = Find(email);
        return user != null && user.Password == passwordHash;
    }

现在关于控制器：为了简化测试，最好使用 IoC 容器，例如 NInject 所以控制器 <-> repo <-> unitOfWork 之间的依赖关系将由 NInject 解决。

这如何使用 Login 方法查看 UserController：

public class UserController: Controller {

    [Ninject.Inject]
    public IUserRepository UserRepository { get; set; }

    public ActionResult Login(AuthorizationViewModel vm) {
        if(ModelState.IsValid) {
            if(UserRepository.Validate(vm.Email, vm.Password)) {
                FormsAuthentication.SetAuthCookie(vm.Email, true);
                if(Url.IsLocalUrl(vm.ReturnUrl)) {
                    return Redirect(vm.ReturnUrl);
                }
                else {
                    return RedirectToAction("Page", "Main");
                }
            }
            else {
                ModelState.AddModelError("", Resources.Validation.WrongEmailOrPassword);
            }
        }

        return View(vm);
    }
}

依赖关系解析可以由自定义控制器工厂完成，如下所示：

public class NInjectControllerFactory: DefaultControllerFactory {
    public IKernel Kernel { get; private set; }

    public NInjectControllerFactory() {
        Kernel = new StandardKernel();
        AddBindings();
    }

    protected override IController GetControllerInstance(System.Web.Routing.RequestContext requestContext, Type controllerType) {
        return controllerType == null
            ? null
            : (IController)Kernel.Get(controllerType);
    }

    private void AddBindings() {
        Kernel.Bind<IUnitOfWork>().To(typeof(EFDbContext)).InRequestScope();
        Kernel.Bind<IUserRepository>().To(typeof(EFUserRepository).InRequestScope();
    }
}

并用您的自定义替换当前控制器工厂。您可以在 Global.asax 的 Application_Start 处理程序中执行此操作：

protected void Application_Start() {
    ...
ControllerBuilder.Current.SetControllerFactory(new NInjectControllerFactory());

}

如果您决定使用 NInject，您可以简单地使用 Nuget 添加它。要启用绑定 InRequestScope，您还需要 NInject.Web.Common。当然，还有很多其他的选择，比如 Castle Windsor 或 StructureMap，但 NInject 是最简单的一种。

希望它会有所帮助。

于 2013-10-31T18:35:21.190 回答