[c#] Email address validation using ASP.NET MVC data type attributes

I have some problems with the validation of a Email.

In my Model:

[Required(ErrorMessage = "Field can't be empty")]
[DataType(DataType.EmailAddress, ErrorMessage = "E-mail is not valid")]
public string ReceiverMail { get; set; }

In my view:

<script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script>
<script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script>

@Html.TextBoxFor(m => m.ReceiverMail, new { @placeholder="E-mail"}) <br />
@Html.ValidationMessageFor(m => m.ReceiverMail)

Now it is correctly showing me "Field can't be empty" when you leave the field empty. But when you fill in an invalid email address like: "fwenrjfw" then the form does not say "E-mail is not valid".

How can I get the form to validate the input as an email address? I am looking for some help with this.

[Required(ErrorMessage = "Please enter Social Email id")]
    [DataType(DataType.EmailAddress)]
    [EmailAddress]
    public string Email { get; set; }

As per the above this will fix server side validation of an Email Address:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }

However...

If you are using JQuery client side validation you should know that the Email validates differently server side (model validation) to client side (JQuery validation). In that test@example (a top level domain email address) would fail server side but would validate fine on the client side.

To fix this disparity you can override the default client side email validation as follows:

$.validator.methods.email = function (value, element) {
    return this.optional(element) || /^[a-z0-9._]+@[a-z]+\.[a-z.]+/.test(value);
}

Used the above code in MVC5 project and it works completely fine with the validation error. Just try this code:

   [Required]
   [Display(Name = "Email")]
   [EmailAddress]

   [RegularExpression(@"^([A-Za-z0-9][^'!&\\#*$%^?<>()+=:;`~\[\]{}|/,?€@ ][a-zA-z0- 
    9-._][^!&\\#*$%^?<>()+=:;`~\[\]{}|/,?€@ ]*\@[a-zA-Z0-9][^!&@\\#*$%^?<> 
        ()+=':;~`.\[\]{}|/,?€ ]*\.[a-zA-Z]{2,6})$", ErrorMessage = "Please enter a 
   valid Email")]


   public string ReceiverMail { get; set; }

Scripts are usually loaded in the end of the html page, and MVC recommends the using of bundles, just saying. So my best bet is that your jquery.validate files got altered in some way or are not updated to the latest version, since they do validate e-mail inputs.

So you could either update/refresh your nuget package or write your own function, really.

Here's an example which you would add in an extra file after jquery.validate.unobtrusive:

$.validator.addMethod(
    "email",
    function (value, element) {
        return this.optional( element ) || /^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/.test( value );
    },
    "This e-mail is not valid"
);

This is just a copy and paste of the current jquery.validate Regex, but this way you could set your custom error message/add extra methods to fields you might want to validate in the near future.

If you are using .NET Framework 4.5, the solution is to use EmailAddressAttribute which resides inside System.ComponentModel.DataAnnotations.

Your code should look similar to this:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }

Try Html.EditorFor helper method instead of Html.TextBoxFor.

I use MVC 3. An example of email address property in one of my classes is:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[Email(ErrorMessage = "The email address is not valid")]
public string Email { get; set; }

Remove the Required if the input is optional. No need for regular expressions although I have one which covers all of the options within an email address up to RFC 2822 level (it's very long).

if you aren't yet using .net 4.5:

/// <summary>
/// TODO: AFTER WE UPGRADE TO .NET 4.5 THIS WILL NO LONGER BE NECESSARY.
/// </summary>
public class EmailAnnotation : RegularExpressionAttribute
{
    static EmailAnnotation()
    {
        DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(EmailAnnotation), typeof(RegularExpressionAttributeAdapter));
    }

    /// <summary>
    /// from: http://stackoverflow.com/a/6893571/984463
    /// </summary>
    public EmailAnnotation()
        : base(@"^[\w!#$%&'*+\-/=?\^_`{|}~]+(\.[\w!#$%&'*+\-/=?\^_`{|}~]+)*"
            + "@"
            + @"((([\-\w]+\.)+[a-zA-Z]{2,4})|(([0-9]{1,3}\.){3}[0-9]{1,3}))$") { }

    public override string FormatErrorMessage(string name)
    {
        return "E-mail is not valid";
    }
}

Then you can do this:

    public class ContactEmailAddressDto
    {
        public int ContactId { get; set; }
        [Required]
        [Display(Name = "New Email Address")]
        [EmailAnnotation] //**<----- Nifty.**
        public string EmailAddressToAdd { get; set; }
    }

You need to use RegularExpression Attribute, something like this:

[RegularExpression("^[a-zA-Z0-9_\\.-]+@([a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,6}$", ErrorMessage = "E-mail is not valid")]

And don't delete [Required] because [RegularExpression] doesn't affect empty fields.

[RegularExpression(@"^[A-Za-z0-9]+@([a-zA-Z]+\\.)+[a-zA-Z]{2,6}]&")]