通用刪除不起作用？

Question

我有一個刪除方法，這個抽象的倉儲類：

public abstract class MyRepository<C, T> : 
     IMyRepository<T> 
     where T : class 
     where C : ObjectContext, new() 
    { 
     private C _entities = new C(); 

     public C Context 
     { 
      get { return _entities; } 
      set { _entities = value; } 
     } 

     public virtual void Delete(T entity) 
     { 
      _entities.Attach(entity); 
      _entities.DeleteObject(entity); 
      _entities.SaveChanges(); 
     } 
    } 

然而，這並不編譯？我如何在這裏創建一個通用的刪除方法？

Answer 1

而是這個

private C _entities = new C(); 

使用Activator.CreateInstance的：

private C _entities = Activator.CreateInstance<T>(); 

Answer 2

修改您的Delete方法如下

public virtual void Delete(T entity) 
    { 
     _entities.CreateObjectSet<T>().Attach(entity); 
     _entities.DeleteObject(entity); 
     _entities.SaveChanges(); 
    } 

    public virtual void Update(T entity) 
    { 
     _entities.CreateObjectSet<T>().Attach(entity); 
     _entities.ObjectStateManager 
      .ChangeObjectState(entity, System.Data.EntityState.Modified); 
     _entities.SaveChanges(); 
    }