Hi, I'm new to Umbraco so please bear with me. Umbraco Version is 7.3.1

I'm aiming to do some quick Razor validation of a form field within a view, inspired by this article: http://www.asp.net/web-pages/overview/ui-layouts-and-themes/validating-user-input-in-aspnet-web-pages-sites

This line gives an error...

Validation.RequireField("comments", "This field is required");

CS0117: 'System.Web.Helpers.Validation' does not contain a definition for 'RequireField'

• I have WebMatrix 3 installed
• Looking at various articles, I don't think it's a typo
• I have allowed client side validation in web config
• I have tried overwriting bin and app_data files (where possible)
• Interestingly I can get output from Validation.Summary

Is this approach still a good one? I appreciate I probably ought to be looking at setting this form up via a Surface Controller, but for a simple requirement, this seemed like a good/fast place to start.

Would be very grateful for any advice, I've spent an entire day on it and have got nowhere. Thanks.