Phone Number Validation MVC

Question

I am trying to use a regular expression to validate a phone number and return an error when an invalid number or phone number is submitted.

MVC Code

Answer 1

To display a phone number with (###) ###-#### format, you can create a new HtmlHelper.

Usage

@Html.DisplayForPhone(item.Phone)

HtmlHelper Extension

public static class HtmlHelperExtensions
{
    public static HtmlString DisplayForPhone(this HtmlHelper helper, string phone)
    {
        if (phone == null)
        {
            return new HtmlString(string.Empty);
        }
        string formatted = phone;
        if (phone.Length == 10)
        {
            formatted = $"({phone.Substring(0,3)}) {phone.Substring(3,3)}-{phone.Substring(6,4)}";
        }
        else if (phone.Length == 7)
        {
            formatted = $"{phone.Substring(0,3)}-{phone.Substring(3,4)}";
        }
        string s = $"{formatted}";
        return new HtmlString(s);
    }
}