将父母转换为儿童

Question

我有几十个域对象(用户,组,角色,社区,帖子等).此外,我有扩展的对象(UserExt,GroupExt等),这些对象派生自那些并包含一些附加数据.在我的数据访问控制层中,有一些检索基础对象的方法.当我需要使用数据填充子对象时,我使用这些方法,但每次我需要将该结果转换为子类型.
因为我不能将父对象转换为子对象,所以我需要为每个父子对提供转换器(通过构造函数,方法,现有转换器的扩展或任何其他方式).这就是我不喜欢的,好像我曾经添加任何字段到基本类型我可能忘记调整我的转换器.是否有更多自动化方式从父母那里填充孩子的字段？
谢谢!

PS:代码:

域对象:

public class Role : OutdoorObject
{
    public String Name { get; set; }
    public Int32 CreatedById { get; set; }
    public Int32 UpdatedById { get; set; }
}

public class RoleExt : Role
{
    public IPrincipal CreatedBy { get; set; }
    public IPrincipal UpdatedBy { get; set; }
}

数据访问层:

public Role GetById(Int32 roleId)
{
    try
    {   
        // seek in cache, return if found
        LQ_Role lqRole = context.LQ_Roles.FirstOrDefault(r => r.RoleID == roleId);
        Role result = LQMapper.LQToObject(lqRole);
        // put result to cache
        return result;
    }
    catch (Exception ex)
    {
        if (ex is BaseRepositoryException) throw ex;
        else throw new UnknownRepositoryException(ex.Message);
    }
}

服务层:

    public Role GetById(IPrincipal Executer, int roleID)
    {
        try
        {
            // perform operation
            Role r = _repo.GetById(roleID);

            // check access
            if (!CanRead(Executer, r)) throw new OperationIsNotPermittedServiceException();

            return r;
        }
        catch (Exception ex)
        {
            // ...
        }
    }

public RoleExt GetExtById(IPrincipal Executer, int roleID)
{
    try
    {
        // perform operation
        Role r = GetById(IPrincipal Executer, int roleID);
        RoleExt result = new RoleExt();
        // here i need to convert r to result
        // and populate addition fields
        result.CreatedBy = userService.GetById(Executer, r.CreatedById);
        result.UpdatedBy = userService.GetById(Executer, r.UpdatedById);

        // check access
        if (!CanRead(Executer, result)) throw new OperationIsNotPermittedServiceException();

        return result;
    }
    catch (Exception ex)
    {
        //...
    }
}

Answer 1

使用反射,这会将所有公共属性从父级复制到子级:

  public static void CopyOver(Parent p, Child c)
  {
      PropertyInfo[] props = p.GetType().GetProperties(BindingFlags.Public);

      foreach( PropertyInfo pi in props)
      {
         pi.SetValue( c, pi.GetValue( p) );
      }
  }