Save after Edit code improvements - asp.net-mvc-3

Question

I'm working on a simple application and am looking to get my head around the CodeFirst EF approach. So far so good.
I have managed to get Create and delete sorted and have got edit working. The thing is I think the edit code could be improved; I'm just not sure how. So here it is:
public ActionResult Edit(int id, CreateResourceViewModel model)
{
if (ModelState.IsValid)
{
// save the changes
//UpdateModel(model.Resource);
//resourceAdminManager.SaveChanges();
Resource current = resourceAdminManager.Resources.Find(id);
current.ResourceTypeID = model.Resource.ResourceTypeID;
current.Name = model.Resource.Name;
current.Description = model.Resource.Description;
current.Email = model.Resource.Email;
current.TurnAroundTime = model.Resource.TurnAroundTime;
resourceAdminManager.SaveChanges();
return RedirectToAction("Index");
}
else
{
return View(model);
}
}
I know there is no exception handling around this, which I need to address but my main concern is the fact that I have manually updated the model. My concerns are:
1. This is in the controller
2. This is hard coded and so any changes to the model will require a re-work of code
Can someone suggest a better way of doing this please.
Many thanks
Nathan
So following on from the AutoMapper suggestions:
This is very helpful and I've started to play with this. I'm running into a little trouble with it.
The contoller now looks like:
if (ModelState.IsValid)
{
try
{
var current = resourceAdminManager.Resources.Find(id);
current = Mapper.Map<CreateResourceViewModel, Resource>(model);
resourceAdminManager.SaveChanges();
return RedirectToAction("Index");
}
catch (Exception exc)
{
ModelState.AddModelError("Error", exc); // or, use a generic error.
}
}
return View(model);
The error occurs in the view when I click save. I get null exception on the following:
<%: Html.DropDownListFor(model => model.Resource.ResourceTypeID, new SelectList(Model.ResourceTypes, "ResourceTypeId", "Title"), "-- Select Resource Type --")%>
Any ideas on what I may be missing here?

Answer 1

One word: AutoMapper.
Will turn those 5 left-to-right boilerplate lines into one.
One of the best MVC (well, C#) add-on's i've ever found.
If implemented correctly (i think your ViewModel may need to change a tad), your action will look like this:
public ActionResult Edit(int id, CreateResourceViewModel model)
{
if (ModelState.IsValid)
{
try
{
var current = resourceAdminManager.Resources.Find(id);
current = Mapper.Map<CreateResourceViewModel,Resource>(model);
resourceAdminManager.SaveChanges();
return RedirectToAction("Index");
}
catch (Exception exc)
{
ModelState.AddModelError("Error", exc); // or, use a generic error.
}
}
return View(model);
}
A warning: this will basically replace the entire entity. So if you only want certain fields changed, only include those in the ViewModel, so the other's will be unchanged. You can also specify "Ignore" in AutoMapper so those fields won't get touched.
And to address your concerns:
This is in the controller
Well actually, it should be. In fact, that's the controllers job - updating the model.
The fact you have boilerplate L-R code is bad, which is why AutoMapper helps.
This is hard coded and so any changes to the model will require a re-work of code
Yup, again - AutoMapper solves this. It works on convention (like MVC), so if you have a proeprty in the ViewModel with the same name as the target model (domain object), you won't have to explicitly map -> it will just work. Furthermore, the mapping is a single static class, so it can be easily maintained.

Answer 2

You are using ViewModel which is very good practise.
1] For Exception handling will suggest to inherit your Controller
from your custom "BaseControllor" instead of System.Web.Mvc.Controller
public class YourController : BaseController
In "BaseControllor" override OnException so that all excptions across your Controllor Actions will be catch in it.
public class BaseController: Controller
{
protected override void OnException(ExceptionContext filterContext)
{
base.OnException(filterContext);
}
}
2] You need to refactor your "Save" code into differnt class in same project or differnt project and differnt Class
3] Yes for any Changes in model you would need to make changes in viewmodel, and in your save logic