Iteration #3 – Add form validation

Comment Posted by jonnylynchy

Sat, 07 Aug 2010 01:19:58 GMT

I've followed this tutorial from iteration #1 with no issues until the Validation. Using your example with MVC 2, I get the following exception when attempting to pass empty values:

Object reference not set to an instance of an object.

Line 14: if (contactToValidate.FirstName.Trim().Length == 0)

When I try to set a break point on the validation in the controller, it breaks in the model designer class before reaching the breakpoint:

Constraint Exception was unhandled by user code

Line 177 of ContactManagerModel.designer.cs --- _FirstName = StructuralObject.SetValidValue(value, false);

Did I miss something when setting up my data model?

Comment Posted by jamieBenzy

Thu, 12 Aug 2010 13:48:26 GMT

I received the same null reference exception. Here's what I did to correct it.

1. changed the inherits overload in the page to: Inherits="System.Web.Mvc.ViewPage

2. changed the return view() overload to - return View(contactToEdit); in ContactController.Edit(Contact contactToEdit)

Comment Posted by kaellinn

Thu, 19 Aug 2010 17:19:16 GMT

jonnylynchy and jamieBenzy:

I ran into this problem also. In order to fix it, I added some boolean short-circuiting to my conditions. For instance, my condition for the FirstName field is now:

if (contactToValidate.FirstName == null || contactToValidate.FirstName.Trim().Length == 0)

If contactToValidate.FirstName is null, C# is smart enough to not even test the second half of the OR statement, so it doesn't generate the error. I added similar tests for the other fields also. Hopefully this helps!

Comment Posted by thebigbull

Tue, 16 Nov 2010 12:37:39 GMT

I cannot believe you did not use string.IsNullOrEmpty("") function to validate strings. Microsoft provides these useful and fancy features but forgets to educate its own developers. that does not seem right.

Comment Posted by prolingua.geo

Thu, 10 Mar 2011 08:25:42 GMT

change the code inside public ActionResult Create([Bind(Exclude = "Id")] Contact contactToCreate) to the following and rebuild your solution and try again.

if (!ModelState.IsValid)

{

if (string.IsNullOrEmpty(contactToCreate.FirstName))

ModelState.AddModelError("FirstName", "First name is required.");

if (string.IsNullOrEmpty(contactToCreate.LastName))

ModelState.AddModelError("LastName", "Last name is required.");

if (string.IsNullOrEmpty(contactToCreate.Phone))

ModelState.AddModelError("Phone", "Invalid phone number.");

else if (contactToCreate.Phone.Length > 0 && !Regex.IsMatch(contactToCreate.Phone, @"(($\d{3}$ ?)|(\d{3}-))?\d{3}-\d{4}"))

ModelState.AddModelError("Phone", "Invalid phone number.");

if (string.IsNullOrEmpty(contactToCreate.Email))

ModelState.AddModelError("Email", "Invalid email address.");

else if (contactToCreate.Email.Length > 0 && !Regex.IsMatch(contactToCreate.Email, @"^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$"))

ModelState.AddModelError("Email", "Invalid email address.");

return View(contactToCreate);

}

else

{

if (contactToCreate.FirstName.Trim().Length == 0)

ModelState.AddModelError("FirstName", "First name is required.");

if (contactToCreate.LastName.Trim().Length == 0)

ModelState.AddModelError("LastName", "Last name is required.");

if (contactToCreate.Phone.Length > 0 && !Regex.IsMatch(contactToCreate.Phone, @"(($\d{3}$ ?)|(\d{3}-))?\d{3}-\d{4}"))

ModelState.AddModelError("Phone", "Invalid phone number.");

if (contactToCreate.Email.Length > 0 && !Regex.IsMatch(contactToCreate.Email, @"^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$"))

ModelState.AddModelError("Email", "Invalid email address.");

if (!ModelState.IsValid)

return View(contactToCreate);

}

try

{

_entities.AddToContacts(contactToCreate);

_entities.SaveChanges();

return RedirectToAction("Index");

}

catch

{

return View(contactToCreate);

}

Comment Posted by Tim.Yamkuza

Wed, 18 May 2011 16:01:19 GMT

What order is the validation done in? I've tried several ideas, including string.IsNullOrEmpty and I always get an unhandled exception in the designer for my model (ContactManagerModel.Designer.cs) as if it validates against the database first and then runs the webpage code...

Comment Posted by basbak

Tue, 06 Sep 2011 10:25:12 GMT

Hello,

I am doing this app with Razor syntax in MVC3, it includes a class for the Contacts using DataAnnotations, yet I can't seem to get the client side validation to fire up.

Any suggestions?

Comment Posted by admiringworm

Wed, 12 Oct 2011 08:11:31 GMT

you need to refer to two scripts to get the DataAnnotations to work correctly in MVC3

you need jquery.validate.min.js and jquery.unobtrusive.min.js (both should be already in the "Scripts" directory. since both of them depends on jquery you would have to refer to it as well. (it should already be in _Layout.cshtml)