Question

I know there are lots of delegate/func examples but I can’t find any examples that will work for me, or I just don’t understand them.

I’m using asp.net MVC for a website, and the website needs some web service calls for an outside application to interact with my app. These all need a function to execute (going to db and whatnot), and return a similar data model every time. I want to wrap each call in a try/catch and populate the model.

Here is the generic code that happens every call.

var model = new ResponseDataModel();
try
{
     //execute different code here
}
catch (Exception ex)
{
    model.Error = true;
    model.Message = ex.ToString();
}
return View(model); // will return JSON or XML depending on what the caller specifies

This is one of the controller methods/ functions that I am using

public ActionResult MillRequestCoil()
{
    var model = new ResponseDataModel();
    try
    {
        /* edit */
        //specific code
        string coilId = "CC12345";

        //additional code
        model.Data = dataRepository.doSomethingToCoil(coilId);

        //replaced code
        //model.Data = new { Coil = coilId, M3 = "m3 message", M5 = "m5 message" };
        model.Message = string.Format("Coil {0} sent successfully", coilId);
    }
    catch (Exception ex)
    {
         model.Error = true;
         model.Message = ex.ToString();
    }
    return View(model);
}

I would like to be able to somehow convert the specific function to a variable to pass into the generic code. I’ve looked at delegates and anonymous funcs but it’s pretty confusing until you do it yourself.

Answer 1

Put the following somewhere accessible:

public static ActionResult SafeViewFromModel(
    Action<ResponseDataModel> setUpModel)
{
    var model = new ResponseDataModel();
    try
    {
        setUpModel(model);
    }
    catch (Exception ex)
    {
        model.Error = true;
        model.Message = ex.ToString();
    }
    return View(model); 
}

and then call it like:

public ActionResult MillRequestCoil()
{
    return MyHelperClass.SafeViewFromModel(model =>
    {
        string coilId = "CC12345";
        model.Data = new {
            Coil = coilId,
            M3 = "m3 message",
            M5 = "m5 message" };
        model.Message = string.Format("Coil {0} sent successfully", coilId);
    });
}