ASP.NET MVC: How can I explain an invalid type violation to an end-user with Html.ValidationSummary?
- by Terminal Frost
Serious n00b warning here; please take mercy!
So I finished the Nerd Dinner MVC Tutorial and I'm now in the process of converting a VB.NET application to ASP.NET MVC using the Nerd Dinner program as a sort of rough template.
I am using the "IsValid / GetRuleViolations()" pattern to identify invalid user input or values that violate business rules. I am using LINQ to SQL and am taking advantage of the "OnValidate()" hook that allows me to run the validation and throw an application exception upon trying to save changes to the database via the CustomerRepository class.
Anyway, everything works well, except that by the time the form values reach my validation method invalid types have already been converted to a default or existing value. (I have a "StreetNumber" property that is an integer, though I imagine this would be a problem for DateTime or any other non-strings as well.)
Now, I am guessing that the UpdateModel() method throws an exception and then alters the value because the Html.ValidationMessage is displayed next to the StreetNumber field but my validation method never sees the original input. There are two problems with this:
While the Html.ValidationMessage does signal that something is wrong, there is no corresponding entry in the Html.ValidationSummary. If I could even get the exception message to show up there indicating an invalid cast or something that would be better than nothing.
My validation method which resides in my Customer partial class never sees the original user input so I do not know if the problem is a missing entry or an invalid type. I can't figure out how I can keep my validation logic nice and neat in one place and still get access to the form values.
I could of course write some logic in the View that processes the user input, however that seems like the exact opposite of what I should be doing with MVC.
Do I need a new validation pattern or is there some way to pass the original form values to my model class for processing?
CustomerController Code
// POST: /Customers/Edit/[id]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Edit(int id, FormCollection formValues)
{
Customer customer = customerRepository.GetCustomer(id);
try
{
UpdateModel(customer);
customerRepository.Save();
return RedirectToAction("Details", new { id = customer.AccountID });
}
catch
{
foreach (var issue in customer.GetRuleViolations())
ModelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
}
return View(customer);
}
