Question

I’m currently working on a MVC.NET 3 application; I recently attended a course by “Uncle Bob” Martin which has inspired me (shamed me?) into taking a hard look at my current development practice, particularly my refactoring habits.

So: a number of my routes conform to:

{controller}/{action}/{type}

Where type typically determines the type of ActionResult to be returned, e.g:

public class ExportController
{
    public ActionResult Generate(String type, String parameters)
    {
        switch (type)
        {
            case "csv":
            //do something
            case "html":
            //do something else
            case "json":
            //do yet another thing
        }    
    }
}

Has anyone successfully applied the “replace switch with polymorhism” refactoring to code like this? Is this even a good idea? Would be great to hear your experiences with this kind of refactoring.

Thanks in advance!

Answer 1

If you wanted to “replace switch with polymorphism” in this case, you could create three overloaded Generate() ActionResult methods. Using custom model binding, make the Type parameter a strongly-typed enum called DataFormat (or whatever.) Then you’d have:

 public ActionResult Generate(DataFormat.CSV, String parameters)
    {
    }

 public ActionResult Generate(DataFormat.HTML, String parameters)
    {
    }

 public ActionResult Generate(DataFormat.JSON, String parameters)
    {
    }

Once you get to this point, you can refactor further to get the repetition out of your Controller.