Peter Bromberg's UnBlog

Recently a colleague remarked that if he got a List of some type out of the ASP.NET Cache, and changed an item, the Cache item would also change. That is correct. Session (InProc) , Cache and Application all return "live" references. A good writeup on this can be found by friend and fellow MVP Rick Strahl here: http://www.west-wind.com/Weblog/posts/1214.aspx If you do not want this behavior, you need to either delete the Session / Cache / Application object and replace it with what you want later, or store a clone by duplicating the object, doing your work on the original that you got out of Cache, then replacing the existing cached item with your clone that was not changed. for example: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; namespace CachebyRef { public class Person { public String FirstName { get; set; } public String LastName { get; set; } } p...

Recently I chimed in on a newsgroup thread to an OP (Original Poster) who was questioning why he was losing Cache items. This individual would load a dataset from the Cache object into a local object to use to perform processing. He had been using httpcontext.current.cache and noticed that sometimes he was not able to get the dataset out of the cache. He tried switching to HttpRuntime.Cache and it seemed to help. The OP claimed that the application is under heavy hits, and once or twice every month he would see this error. He wanted to know why does the HttpContext.Current.Cache call work sometimes, while some other times does not. A couple of posters replied, one of whom is a respected MVP who usually makes very astute, high-quality posts. He posted," The cache is only valid during the life of the request. how is you[sic] code using the cache?" Somebody else (also pretty astute, usually) responded, "Cache is valid during lifetime of application not request.....". W...