Question

Have a generic class that inherits from a non-generic class like the structure below:

public class Result
{
     public string ErrorCode { get; set;}
     public string ErrorMessage { get; set;}
     public boo Success { get; set;}
     //Lots more properties

     public ClientResult ToClientResult()
     {
         //some pretty involved calculations of error coded and status
     }
 }

 public class Result<T> : Result
 {
     public T details {get; set;}

     public ClientResult<T> ToClientResult<T>()
     {
        //Need to call the parent class implementation and convert result to  generic ver  
     }
 }

My question is how can i call the parent ToClientResult() and convert the result to the generic version of ClientResult<T> and then i need to set a property of the ClientResult<T> to the details property of the Result<T> class.

I am sure i am missing an easy solution here, i really dont want to duplicate the parent class logic as it is pretty complicated.

Answer 1

You can’t cast an object of the parent type to a child type if it’s created as the parent type (using new ClientResult()). It just doesn’t work that way.

What you could do is factor the complicated code out to another method which you use to do the heavy lifting in both the Result class and the Result<T> class:

public class Result
{
    public string ErrorCode { get; set;}
    public string ErrorMessage { get; set;}
    public boo Success { get; set;}
    //Lots more properties

     public ClientResult ToClientResult()
     {
         var clientResult = new ClientResult();
         SetupClientResult(clientResult);
         return clientResult;
     }

     protected void SetupClientResult(ClientResult clientResult) 
     {    
         //some pretty involved calculations of error coded and status           
     }

}

public class Result<T> : Result
{
     public T details {get; set;}

     // This now shadows the original ToClientResult method. The trap here is that if
     // you are treating your Result<T> instance as a Result, this method will not be 
     // called, and the return type will be ClientResult and not ClientResult<T>.
     // See: http://stackoverflow.com/questions/392721/difference-between-shadowing-and-overriding-in-c?lq=1
     public ClientResult<T> ToClientResult()
     {
         var clientResult = new ClientResult<T>();
         SetupClientResult(clientResult);

         clientResult.SomeProperty = details;

         return clientResult;
     }
}

This is all assuming ClientResult<T> derives from ClientResult, which is a little hard to tell from your question.