Adding custom placeholders for email in Episerver Forms

CustomDefaultPlaceHolderProvider.cs

using EPiServer;
using EPiServer.Core;
using EPiServer.Forms.Core.Internal;
using EPiServer.Forms.Core.Models;
using EPiServer.ServiceLocation;
using Gosso.EpiserverSite.Mvc.Models.Pages;
using System.Collections.Generic;
using System.Web;

namespace Gosso.EpiserverSite.Mvc.Business.Forms
{
    public class CustomDefaultPlaceHolderProvider : IPlaceHolderProvider
    {
        private readonly IContentRepository contentRepository = ServiceLocator.Current.GetInstance<IContentRepository>();

        public new IEnumerable<PlaceHolder> ExtraPlaceHolders
        {
            get
            {
                        public IEnumerable<PlaceHolder> ExtraPlaceHolders => new PlaceHolder[] {
                        new PlaceHolder("PageEmail", string.Empty),
                        new PlaceHolder("OrderInformation", string.Empty),
                        new PlaceHolder("PageUrl", string.Empty) };
            }
        }

        public new IEnumerable<PlaceHolder> ProcessPlaceHolders(IEnumerable<PlaceHolder> availablePlaceHolders, FormIdentity formIden, HttpRequestBase requestBase, Submission submissionData, bool performHtmlEncode)
        {
            // run default
            IEnumerable<PlaceHolder> plh = base.ProcessPlaceHolders(availablePlaceHolders, formIden, requestBase, submissionData, performHtmlEncode);

            var processPlaceHolders = availablePlaceHolders as PlaceHolder[] ?? availablePlaceHolders.ToArray();
            foreach (PlaceHolder holder in processPlaceHolders)
            {
                if (holder.Key == "PageEmail")
                {
                    var email = "[email protected]";
                    int id = int.Parse(submissionData.Data["SYSTEMCOLUMN_HostedPage"] + "");

                    PageData containingPage = _contentRepository.Get<PageData>(new ContentReference(id));
                    if (containingPage is TypeWithEmail)
                        email = containingPage.GetPropertyValue<String>("Email","[email protected]");

                    holder.Value = email;
                }

                if (holder.Key == "PageUrl")
                {
                    if (requestBase.UrlReferrer != null) holder.Value = requestBase.UrlReferrer.ToString();
                }
                
                if (holder.Key == "OrderInformation")
                {
                    if (requestBase.UrlReferrer != null)
                    {
                        var orderpage = GetOrderPageData(requestBase);
                        if (orderpage!=null)
                            holder.Value = $"Name: {orderpage.PageName} <br/>OrderNo:{((orderpage as TypeWithOrderno) == null ? string.Empty : (orderpage as TypeWithOrderno).OrderNumber)} <br/>Page ID: {orderpage.PageLink.ID.ToString(CultureInfo.InvariantCulture)}";
                    }
                }
            }

            return plh;
        }
        
        private PageData GetOrderPageData(HttpRequestBase requestBase)
        {
            const string orderidname = "orderid";
            string orderref = null;
            if (requestBase.UrlReferrer != null)
            {
                orderref = HttpUtility.ParseQueryString(requestBase.UrlReferrer.Query)[orderidname];//UrlReferrer = {http://localhost:17000/ordersida/?orderid=3296}
            }
            if (orderref == null && requestBase.QueryString[orderidname] != null)
            {
                orderref = requestBase.QueryString[orderidname];
            }
            if (orderref == null)
                return null;
            int orderid = 0;
            int.TryParse(orderref, out orderid);

            return orderid > 0 ? _contentRepository.Get<PageData>(new ContentReference(orderid)) : null;
        }


    }
}