Creating an interface to have a generic List object

Question

I have a data structure something like this:

public class HighLevelConversionData
{
    public int customerID {get;set;}
    public string customerName {get;set;}
    public decimal amountSpent {get;set;}
}

This data will be accessed by a third party and a GWT front end, meaning I'll be using web services to move the data around. The customer is also of a different localisation than the dev team, so I'm wanting to send status messages as a wrapper for the returned data items, like so:

public class HighLevelConversionDataWrapper
{
    public int StatusCode {get;set;}
    public string StatusMessage {get;set;}
    public List<HighLevelConversionData> {get;set;}
}

However I'd rather have an interface for these methods to inherit from, to ensure we're always sending the statuscode & message in the same way. But my understanding of how generics work in an interface seems to be failing me. I believe it should be something like:

public Interface IServiceWrapper
{
    public int StatusCode {get;set}
    public string StatusMessage {get;set;}
    public List<T> ReturnedData {get;set;}
}

But I've come unstuck here.

Answer 1

Something like this?

public class ConcreteWrapper : IServiceWrapper<HighLevelConversionData>
{
    public int StatusCode {get;set;}
    public string StatusMessage { get; set; }
    public List<HighLevelConversionData> ReturnedData { get; set;}
}

public class HighLevelConversionData
{
    public int customerID {get;set;}
    public string customerName {get;set;}
    public decimal amountSpent {get;set;}
}

public interface IServiceWrapper<T>
{
    int StatusCode { get; set; }
    string StatusMessage { get; set; }
    List<T> ReturnedData { get; set;}
}

Answer 2

If the interface has generic type parameters, the interface itself must be generic, so you'll need to do:

public interface IServiceWrapper<T> 
{     
  public int StatusCode {get;set}     
  public string StatusMessage {get;set;}     
  public List<T> ReturnedData {get;set;} 
} 

and then specify the type parameters in the code like this:

public class HighLevelConversionDataServiceWrapper 
          : IServiceWrapper<HighLevelConversionData>
{
   public List<HighLevelConversionData> ReturnedData {get;set;} 
}