LINQ to SQL, Generalization

Question

Hi All,

I am struggling a bit to figure this one out.

I'm working on an ASP.NET MVC project, using LINQ to SQL for my data layer. The database consists of 10 or so different "exceptions" tables, e.g. "Exceptions.LADM", "Exceptions.USB", "Exceptions.GPO". Basically these tables are tracking user+machine information for relaxation of various security procedures.

My LINQ to SQL model has been generated. I have different classes for each table available to me. However, I am not sure how to use them in controller without having to generate separate Controller Actions for each exception type. For List action, I want to do something like this:

// Example Request:  /Exceptions/List/ladm
// Routing:   Controller = "Exceptions", Action = "List", type = "ladm"

// Controller Action:

public ActionResult List(string type)
{
    string viewname = "List-" + type;   // refer to "List-ladm" view.
    if(type == "ladm")
    {
       var items = _repository.ListAllLADMExceptions();
    }

    return View(viewname, items);
}

My repository implements ListAll<XXXXXX>Exceptions methods for each table. Is there a way to avoid 10 different if/else statements? It looks ugly and I'm sure there is a better way that I cannot think of. May be I'm approaching it from incorrect angle.

Any suggestions would be welcomed.

Thanks.

Answer 1

You could try dynamic method dispatching by using reflection (it's pretty costly, performance-wise):

object items = _repository.GetType().GetMethod("ListAll"+type+"Exceptions")
                          .Invoke(_repository, null);

I would write a switch statement (not if/else) for 10 cases however. It's not that bad.

switch (type) {
    case "ladm": return View("ladm", _repository.ListAllLADMExceptions());
    case "....": return View(....);
}

Answer 2

The typical pattern is one controller per table. How about repartitioning the variability into multiple controller classes using a common base class? Something like this:

public abstract class ExceptionsBaseController<T> : Controller where T:class 
{
 protected abstract Table<T> ExceptionsTable { get; }

 public virtual ActionResult List()
 {
  var items = ExceptionsTable;
  return View(items);
 }
}

One benefit as I see it would be easier to handle differences between the exception classes and add new ones. It probably won't help your total code line count though, but maybe it can awake ideas.