Question

I am adding a bunch of items to the ASP.NET cache with a specific prefix. I’d like to be able to iterate over the cache and remove those items.

The way I’ve tried to do it is like so:

    foreach (DictionaryEntry CachedItem in Cache)     {         string CacheKey = CachedItem.Key.ToString();         if(CacheKey.StartsWith(CACHE_PREFIX){             Cache.Remove(CacheKey);         }     } 

Could I be doing this more efficiently?

I had considered creating a temp file and adding the items with a dependancy on the file, then just deleting the file. Is that over kill?

Answer 1

You can’t remove items from a collection whilst you are iterating over it so you need to do something like this:

List<string> itemsToRemove = new List<string>();  IDictionaryEnumerator enumerator = Cache.GetEnumerator(); while (enumerator.MoveNext()) {     if (enumerator.Key.ToString().ToLower().StartsWith(prefix))     {         itemsToRemove.Add(enumerator.Key.ToString());     } }  foreach (string itemToRemove in itemsToRemove) {     Cache.Remove(itemToRemove); } 

This approach is fine and is quicker and easier than cache dependencies.