Is it possible to clear the ASP.NET application Cache without resetting the AppDomain?

Question

I would like to reset/clear an item in the Cache, but without resetting the application or writing a specialized page just for this. ie, a non-programmatic solution. Is this possible?

Solution 1

Short answer: No.

ASP.NET Cache doesn't have a administration interface to manage it. You'll need to recycle your application pool, or to to create a simple page to do Delete Items from the Cache in ASP.NET.

EDIT: Inspired on Mick answer, you could to have a page like this (RemoveCache.aspx):

<%@ Page Language="C#" %>
<script runat="server">

    void Page_Load(object sender, EventArgs e)
    {
        if (String.IsNullOrEmpty(Request.QueryString["name"]))
        {
            foreach (DictionaryEntry item in Cache)
            {
                Cache.Remove(item.Key.ToString());
                Response.Write(item.Key.ToString() + " removed<br />");
            }
        }
        else
        {
            Cache.Remove(Request.QueryString["name"]);
        }
    }

</script>

If you call RemoveCache.aspx all your cache will be removed; running RemoveCache.aspx?name=Products, just Products cache entry will be removed.

Solution 2

            Dim CacheKeys As New List(Of String)
            For Each CacheItem As DictionaryEntry In Cache
                CacheKeys.Add(CacheItem.Key)
            Next

            For Each Key As String In CacheKeys
                Cache.Remove(Key)
            Next

This appears to go through the cache and clear the items but it does not clear the Response cache. If you login to a webpage using FormsAuthentication, goto a webpage, logout, then just type that URL into the address bar it return you to that page. When you click on anything it return you to the login page because you are not authenticated but the page still displays from the cache even though the cache is cleared when the logout button is clicked. Setting the Cachability to NoCache does not work because all GridViews that use DataBound event show as expired when using the back button. I am still looking for a proper cache clearing solution for this case.

Solution 3

Only have VB.NET code to hand, but why not loop through the cache removing items?

For Each de As DictionaryEntry In HttpContext.Current.Cache

HttpContext.Current.Cache.Remove(DirectCast(de.Key, String))

Next

Regards

Comments

[SLaks]

This will not work. You can't modify a collection in a For Each loop.

[SLaks]

This will not work. You can't modify a collection in a foreach loop.

[Rubens Farias]

@Slaks, I just ran here without major problems (just a missing .ToString()); can you please confirm that problem?

[Bryan]

OK, thanks fellas. But writing new code requires resetting the AppDomain. I'm not scared to write code, just wanted to do it without resetting the app!

[SLaks]

I just checked the source. Calling GetEnumerator makes a complete copy of the cache, so it isn't a correctly behaved enumerator.

[Ankur-m]

This will throw an exception if the Cache Collection is modified. You may like to check this link - stackoverflow.com/questions/6212676/…