We did this. It basicly creates a cached version of a page for each user.

public override string GetVaryByCustomString(System.Web.HttpContext context, string custom)
        {          
            string result = base.GetVaryByCustomString(context, custom);

            if (string.IsNullOrEmpty(custom))
            {
                return result;
            }

            result = string.Empty;

            var keys = custom.Split(new[] { ";" }, StringSplitOptions.RemoveEmptyEntries).ToList();

            if (keys.Contains(Caching.VarByCustomKeys.Url))
            {
                result += string.Format("url={0};", context.Request.Url.AbsoluteUri);
            }

            if (keys.Contains(Caching.VarByCustomKeys.User))
            {
                if (Member.IsLoggedOn())
                {
                    result += string.Format("user={0};", Member.CurrentMemberId());
                }
            }

            // handle preview mode caching
            if (UmbracoContext.Current.InPreviewMode)
            {
                // store timestamp on first request
                var ticks = DateTime.Now.Ticks;
                if (HttpContext.Current.Items.Contains("ticks"))
                {
                    ticks = (long)HttpContext.Current.Items["ticks"];
                }
                else
                {
                    HttpContext.Current.Items.Add("ticks",ticks);
                }

                // cache by page id and timestamp
                result += string.Format("preview={0};date={1};", UmbracoContext.Current.PageId, ticks);
            }

            return result;
        }

Dave

Hello,

With donut cache you can also uncache certain parts of the page. This can be done with an html.action:

@Html.Action("ShowDates", "Newsoverview", true)

The third parameter says exclude from parent cache. So the route hijacked controller and view are cached, but all logic done in the html action and it's view isn't. You can find an example in the best practises.

https://github.com/jbreuer/Hybrid-Framework-for-Umbraco-v7-Best-Practises/blob/master/Umbraco.Site/Views/NewsOverview.cshtml#L76

https://github.com/jbreuer/Hybrid-Framework-for-Umbraco-v7-Best-Practises/blob/master/Umbraco.Extensions/Controllers/NewsoverviewController.cs#L35

So you can put the custom content for the member in the html.action so that doesn't get cached. That's the whole principle of Donut Cache.

Jeroen

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