ASP.NET MVC How to get Custom Validators to work with Client Side Validation

Question

The following validation works fine on both client side and server side

    <DisplayName("website")> _
    <StringLength(256, ErrorMessage:="Web Address cannot exceed 256 characters.")> _
    <RegularExpression("^http(s?)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(/\S*)?$", ErrorMessage:="Not a valid website address")> _
    Public Property WebSite As String

However this validation only works on the Server side

    <DisplayName("website")> _
    <StringLength(256, ErrorMessage:="Web Address cannot exceed 256 characters.")> _
    <Website(ErrorMessage:="Not a valid website address")> _
    Public Property WebSite As String

Where my custom WebsiteAttribute looks like this

Public Class WebsiteAttribute : Inherits RegularExpressionAttribute
    Public Sub New()
        MyBase.new("^http(s?)\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(/\S*)?$")
    End Sub
End Class

I'm obviously missing something very simple.

Thanks in advance.

Answer 1

Take a look at this blog post from Phil Haack which demonstrates how to setup client validation for custom attributes. Basically you will need to write and register a custom DataAnnotationsModelValidator<T>.