SitefinityUserControl

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using Telerik.Sitefinity.Data;
using Telerik.Sitefinity.Services;
using Telerik.Sitefinity.Web;

namespace SitefinityWebApp.Websilk.CustomControls {
    public enum CacheLevel
    {
        NeverCache,
        ContentListener,
        AlwaysCache
    }

    public abstract class SitefinityUserControl : UserControl {
        protected abstract CacheLevel ControlCacheLevel {
            get;
        }

        protected virtual List<CacheDependencyKey> GetCacheDependencyObjects() {
            return null;
        }

        protected void SubsribeCacheDependency() {
            if (ControlCacheLevel == CacheLevel.ContentListener && !this.IsBackend()) {
                var cacheDependencyObjects = this.GetCacheDependencyObjects();

                if (cacheDependencyObjects != null) {
                    if (!SystemManager.CurrentHttpContext.Items.Contains(PageCacheDependencyKeys.PageData)) {
                        SystemManager.CurrentHttpContext.Items.Add(PageCacheDependencyKeys.PageData, new List<CacheDependencyKey>());
                    }

                    ((List<CacheDependencyKey>)SystemManager.CurrentHttpContext.Items[PageCacheDependencyKeys.PageData]).AddRange(cacheDependencyObjects);
                }
            }
        }

        protected virtual void Page_PreRender(object sender, EventArgs e) {
            if (ControlCacheLevel == CacheLevel.ContentListener) {
                SubsribeCacheDependency();
            } else if (ControlCacheLevel == CacheLevel.NeverCache) {
                Response.Cache.SetCacheability(HttpCacheability.NoCache);
            }
        }
    }
}