Crownpeak Input Validation Cheat Sheet by GregFinzer

Input.ShowHeader("Contact Us");
Input.ShowTextBox("Page Title", "page_title");
Input.ShowWysiwyg("Address", "address", ServicesInput.FullWYSIWYG());
Input.ShowTextBox("Customer Service Phone", "customer_service_phone");
Input.ShowTextBox("Email", "email");

<h1><%= asset["page_title"] %></h1>
<p><%= asset["address"] %></p>
<p><%= asset["customer_service_phone"] %></p>
<p><a href='mailto:<%= asset["email"] %>'><%= asset["email"] %></a></p>

using System.Text.RegularExpressions;
using CrownPeak.CMSAPI;
/ Some Namespaces are not allowed. /
namespace Developer_Training.Project.Library
{
    public static class PostInputHelper
    {
        public static bool RequiredField(Asset asset, PostInputContext context, string field)
        {
            bool isValid = true;

            if (!context.InputForm.HasField(field))
            {
                context.ValidationErrorFields.Add(field, "This is a required field");
                isValid = false;
            }
            else if (!asset.Label.Equals(context.InputForm[field]))
            {
                asset.Rename(context.InputForm[field]);
            }

            return isValid;
        }

        public static bool ValidEmail(Asset asset, PostInputContext context, string field)
        {
            bool isValid = true;
            if (!Regex.IsMatch(context.InputForm[field], @"[@\s]+@[@\s]+\.[@\s]+$"))
            {
                context.ValidationErrorFields.Add(field, "Please enter a valid email address");
                isValid = false;
            }
            else if (!asset.Label.Equals(context.InputForm[field]))
            {
                asset.Rename(context.InputForm[field]);
            }

            return isValid;
        }
    }
}

PostInputHelper.RequiredField(asset, context, "page_title");
PostInputHelper.ValidEmail(asset, context, "email");