The DataAnnotations validator not working in asp.net mvc 4 razor view, when using the special characters in the regular expression.
Model:
The problem is that the regex pattern is being HTML encoded twice, once when the regex is being built, and once when being rendered in your view.
For now, try wrapping your TextBoxFor in an Html.Raw, like so:
Html.Raw
@Html.Raw(Html.TextBoxFor(model => Model.FirstName, new { }))