I have a simple form on an ASP.NET MVC site that I'm building. This form is submitted, and then I validate that the form fields aren't null, empty, or improperly formatted.
However, when I use ModelState.AddModelError()
to indicate validation errors from my controller code, I get an error when my view is re-rendered. In Visual Studio, I get that the following line is highlighted as being the location of the error:
<%=Html.TextBox("Email")%>
The error is the following:
NullReferenceException was unhandled by user code - object reference not set to an instance of an object.
My complete code for that textbox is the following:
<p>
<label for="Email">Your Email:</label>
<%=Html.TextBox("Email")%>
<%=Html.Va开发者_JAVA百科lidationMessage("Email", "*") %>
</p>
Here's how I'm doing that validation in my controller:
try
{
System.Net.Mail.MailAddress address = new System.Net.Mail.MailAddress(email);
}
catch
{
ModelState.AddModelError("Email", "Should not be empty or invalid");
}
return View();
Note: this applies to all of my fields, not just my Email field, as long as they are invalid.
That's a horrible bug/feature (call in whatever) in ASP.NET MVC the helper that you may fix by calling SetModelValue like this:
ModelState.AddModelError("Email", "Should not be empty or invalid");
ModelState.SetModelValue("Email", new ValueProviderResult("raw value", "attempted value", CultureInfo.InvariantCulture));
By the way is there any reason you would write all this code when you could simply annotate your view model:
public class SomeViewModel
{
[RegularExpression("Some bulletproof regex you could google to validate email address", ErrorMessage = "Should not be empty or invalid")]
public string Email { get; set; }
}
and leave the data binder do the heavy lifting.
I am unable to reproduce.
Action
[HttpPost]
public ActionResult Index(string email)
{
if (string.IsNullOrEmpty(email))
{
ModelState.AddModelError("Email", "Should not be empty or invalid");
}
return View();
}
View
<%using (Html.BeginForm() { %>
<p>
<label for="Email">
Your Email:</label>
<%=Html.TextBox("Email")%>
<%=Html.ValidationMessage("Email", "*") %>
<input type="submit" />
</p>
<%} %>
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