Question

I can’t get client side validation of regular expressions working with MVC3RTM. All other client side validation works when I comment out the RegularExpression attribute so I know it’s the one causing me problems.

I have a simple model. (SiteText and SiteErrors are just resource files)

 public class NewUser {

        [Required]
        [MultiCulturalDisplayName("UserName", typeof(SiteText))]
        public string UserName { get; set; }

        [Required]
        [AllowHtml]
        [RegularExpression(RegExConstants.EmailRegEx, ErrorMessageResourceType = typeof(SiteErrors), ErrorMessageResourceName = "EmailInvalid")]
        [DataType(DataType.EmailAddress)]
        [MultiCulturalDisplayName("EmailAddress", typeof(SiteText))]
        public string Email { get; set; }

        [Required]
        [ValidatePasswordLength]
        [DataType(DataType.Password)]
        [MultiCulturalDisplayName("Password", typeof(SiteText))]
        public string Password { get; set; }

        [DataType(DataType.Password)]
        [MultiCulturalDisplayName("PasswordConfirm", typeof(SiteText))]
        [Compare("Password", ErrorMessageResourceType = typeof(SiteErrors), ErrorMessageResourceName = "PasswordCompare")]
        public string ConfirmPassword { get; set; }
    }

Here is the C# escaped regex string that I store in a constant.

^((?>[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+\\x20*|\"((?=[\\x01-\\x7f])[^\"\\\\]|\\\\[\\x01-\\x7f])*\"\\x20*)*(?<angle><))?((?!\\.)(?>\\.?[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+)+|\"((?=[\\x01-\\x7f])[^\"\\\\]|\\\\[\\x01-\\x7f])*\")@(((?!-)[a-zA-Z\\d\\-]+(?<!-)\\.)+[a-zA-Z]{2,}|\\[(((?(?<!\\[)\\.)(25[0-5]|2[0-4]\\d|[01]?\\d?\\d)){4}|[a-zA-Z\\d\\-]*[a-zA-Z\\d]:((?=[\\x01-\\x7f])[^\\\\\\[\\]]|\\\\[\\x01-\\x7f])+)\\])(?(angle)>)$

Here is the un-escaped version.

^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*")@(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])[^\\\[\]]|\\[\x01-\x7f])+)\])(?(angle)>)$

Could the regex perhaps be too long?

Answer 1

Regular expression arguments aside – have a look at my blog post about how to get Email validation working on the client using ASP.NET MVC 3 and unobtrusive validation.

This approach uses the built-in jQuery Validation email validation and not your own regex. But will use your regex on the server side. I don’t know what sort of regex jQuery validation uses, so this could be a good or bad thing.

ASP.NET MVC 3 Email Validation with Unobtrusive jQuery Validation

It’s extremely simply and if you want to change the regex, just plug your own one in there.

This is the guts of it:

namespace PageDesigners.Library.ValidationAttributes
{
    public class EmailAttribute : RegularExpressionAttribute, IClientValidatable
    {
        public EmailAttribute()
            : base(@"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
                   @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
                   @".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$")
        {
        }

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        {
            var errorMessage = FormatErrorMessage(metadata.GetDisplayName());

            yield return new EmailValidationRule(errorMessage);
        }
    }

    public class EmailValidationRule : ModelClientValidationRule
    {
        public EmailValidationRule(string errorMessage)
        {
            ErrorMessage = errorMessage;
            ValidationType = "email";
        }
    }
}