Question

for object serialization I created a DataTransferObject-Pendant for each of my objects. Each original object gets a ToDTO()-method that returns the appropriate DTO-Object with the properties to be saved . Most of my original objects are inherited from an other, so I would want each inheritance-level to care for their own properties. A simple example:

class base
{
  private string _name;

  public DTO_base ToDTO()
  {
    DTO_base result = new DTO_base();
    result.Name = _name;
    return result;
  }
}

The inherited class should override the ToDTO() method, calling the parents method and adding its own properties to be saved, like:

class inherited : base
{
  private string _description;

  public new DTO_inherited ToDTO()
  {
    DTO_inherited result = base.ToDTO();
    result.Description = _description;
    return result;
  }
}

Obviously, this wont work, because base.ToDTO() returns a DTO_base object. Can anyone suggest, how this feature would be implemented best?

Thanks in advance,
Frank

Answer 1

I would use a Template Method:

class baseCls
{
  private string _name;

  public DTO_base ToDTO()
  {
    DTO_base result = createDTO();
    result.Name = _name;
    setAdditionalData(result);
    return result;
  }

  protected abstract DTO_base createDTO();
  protected abstract void setAdditionalData(DTO_base dto);
}

class inherited : baseCls
{
  private string _description;

  protected override DTO_base createDTO() {
    return new DTO_inerited();
  }
  protected override void setAdditionalData(DTO_base dto) {
     inherited i = (DTO_inherited)dto;
     i.Description = _Description;
  }
}