Episerver CMS editable cache attribute.

EditableCacheAttribute.cs

namespace Demo
{
    public class EditableCacheAttribute : ContentOutputCacheAttribute
    {
        public EditableCacheAttribute()
        {
            UseOutputCacheValidator = UseOutputCache;
        }

        private static bool UseOutputCache(IPrincipal principal, HttpContextBase context, TimeSpan duration)
        {
           var useOutputCache = false;
            
           if (!principal.Identity.IsAuthenticated && duration != TimeSpan.Zero)
           {
                if (string.Equals(context.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase))
                {
                    useOutputCache = true;
                    var url = context.Request.Url?.ToString();
                    var content = UrlResolver.Current.Route(new UrlBuilder(url)) as PageData;
                    var proxyCacheTime = new TimeSpan(0, 0, 600); //default time: 10 minutes

                    if (content is ICacheSettings cacheSettings)
                    {
                        useOutputCache = cacheSettings.DisableOutputCache != true; //check if output cache is disabled by editor
                        proxyCacheTime = cacheSettings.CdnCacheTime > 0 ? new TimeSpan(0, 0, cacheSettings.CdnCacheTime) : proxyCacheTime; //override cache time with editor setting
                    }

                    if (useOutputCache)
                    {
                        var eTag = content?.Saved.Ticks.ToString() ?? string.Empty;
                        context.Response.Cache.SetETag(eTag);
                        context.Response.Cache.SetProxyMaxAge(proxyCacheTime);
                        context.Response.Cache.SetMaxAge(proxyCacheTime);
                    }
                }
            }

            return useOutputCache;
        }
    }
}