Generic interface problem

Question

I'd like to have one interface for all my grid related tasks.The tasks implement this interface:

public interface IDataForGrid<T>
{
    IGridResponse<T> GetList(IGridRequest request);
}

The T type is always a DTO class. I cant't create a common interface for this DTOs because they have nothing common.Just a dumb DTO with particular properties.

I'd like to use it like this :

public class Service1
{
    public IGridResponse CreateResponse(IGridRequest request)
    {

        ...
        IDataForGrid<T> aa;

        if(request == 1) aa = new CustomerGridData;
        if(request == 2) aa = new OrderGridData;

        var coll = aa.GetList();
    }
}

public class CustomerGridData : IDataForGrid<CustomerDTO>
{
   ...
}

The problem is I don't know what to put instead of the T.

Sustentation

There was an error in my post, it's fixed now – Sustentation

What are you going to do with coll ? – Luger

follow up question asked over here #2424787 – Frail

Answer 1

Maybe Im miss-understanding you, but couldnt you make a super class that all of your DTO's like BaseDTO

Then use it like so:

public class CustomerDTO : BaseDTO {}

IDataForGrid<BaseDTO> aa;

var coll = aa.GetList();

This way, your coll variable will be of type IGridResponse<BaseDTO> which all of your DTO object extend from.

That make sense?

Kingsize

Yes, you understood it well. But what to put in the base class ? The DTOs have nothing common. – Sustentation

you technically dont need anything in the base class, although having nothing in there sort of feel weird. But if thats the cost of getting your way in other more detailed areas of your code, then so be it. Chances are that in the future your DTO's will end up having something in common anyways, they usually do :) – Kingsize

will you not get a cast exceptions when casting? IDataForGrid<object> aa = new CustomerDataGrid(); – Leshia

Answer 2

You can make the method generic as well so that T can be substituted as required:

public class Service1
{
  public IGridResponse<T> CreateResponse<T>(IGridRequest request)
  {
    ...
    IDataForGrid<T> aa;

    if(request == 1) cg = new CustomerGridData;
    if(request == 2) og = new OrderGridData;

    var coll = aa.GetList();
  }
}

Openmouthed