ASP.NET Object Caching in a Class

Question

I'm trying to create a Caching Class to cache some objects from my pages. The purpose is to use the Caching system of the ASP.NET framework but to abstract it to separate class. It seems that the caching doesn't persist.

Any ideas what I'm doing wrong here? Is it possible at all to cache object out side the Page it self?

EDIT: added the code:

Insert to cache

Cache c = new Cache();
c.Insert(userid.ToString(), DateTime.Now.AddSeconds(length), null, DateTime.Now.AddSeconds(length), Cache.NoSlidingExpiration,CacheItemPriority.High,null);

Get from the cache

DateTime expDeath = (DateTime)c.Get(userid.ToString())

I get null on the c.Get, even after I did have the key.

The code is in a different class than the page itself (the page uses it)

Thanks.

Please post your code for this class. You might be doing one of a million things wrong, so we need to see the code in order to figure it out. — Oded
– Oded, Commented Jan 3, 2011 at 15:24

Matthew Abbott · Accepted Answer · 2011-01-03 15:47:55Z

7

There are numerous ways you can store objects in ASP.NET

Page-level items -> Properties/Fields on the page which can live for the lifetime of the page lifecycle in the request.
ViewState -> Store items in serialised Base64 format which is persisted through requests using PostBack. Controls (including the page itself - it is a control) can preserve their previous state by loading it from ViewState. This gives the idea of ASP.NET pages as stateful.
HttpContext.Items -> A dictionary of items to store for the lifetime of the request.
Session -> Provides caching over multiple requests through session. The session cache mechanism actually supports multiple different modes.
- InProc - Items are stored by the current process, which means should the process terminate/recycle, the session data is lost.
- SqlServer - Items are serialised and stored in a SQL server database. Items must be serialisable.
- StateServer - Items are serialised and stored in a separate process, the StateServer process. As with SqlServer, items must be serialisable.
Runtime - Items stored in the runtime cache will remain for the lifetime of the current application. Should the applciation get recycled/stop, the items will be lost.

What type of data are you trying to store, and how do you believe it must be persisted?

Right at the beginning of last year I wrote a blog post on a caching framework I had been writing, which allows me to do stuff like:

// Get the user.
public IUser GetUser(string username)
{
  // Check the cache to find the appropriate user, if the user hasn't been loaded
  // then call GetUserInternal to load the user and store in the cache for future requests.
  return Cache<IUser>.Fetch(username, GetUserInternal);
}

// Get the actual implementation of the user.
private IUser GetUserInternal(string username)
{
  return new User(username);
}

That was nearly a year ago, and it has been evolved a bit since then, you can read my blog post about it, let me know if thats of any use.

edited Jan 3, 2011 at 15:47

answered Jan 3, 2011 at 15:32

Matthew Abbott

61.7k9 gold badges108 silver badges131 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Roman Over a year ago

I have only a datetime object to store - and I need it being persisted between sessions (something like the Application object but the caching abilities). Maybe I could pass the HttpContext.Current.Cache to the function to use it to store the object?

Matthew Abbott Over a year ago

That wouldn't be a bad idea, instead of creating a new instance of the Cache which likely wouldn't be persisted between requests, pass the runtime cache (HttpRuntime.Cache or HttpContext.Current.Cache [they are the same cache instance]). Make sure you control how the cache is being used though...

Roman Over a year ago

Thanks - I just needed to pass the HttpContext.Current.Cache to the function. +1 for the great answer :)

Shreedhar Kotekar Over a year ago

Thanks for summarizing stores at each level. I was looking to persist something at request level, an object created when request is received and lives until the request is active. I did not know about HttpContext.Items before this. Thank you very much.

Oded · Accepted Answer · 2011-01-03 15:33:00Z

3

Your cache reference needs to be accessible to all items in your code - the same reference.

If you are newing up the Cache class every time, you are doing it wrong.

answered Jan 3, 2011 at 15:33

Oded

501k102 gold badges900 silver badges1k bronze badges

3 Comments

Roman Over a year ago

How should it be done? Should i Pass the HttpContext.Current.Cache object to the function?

Oded Over a year ago

@roman - is this an ASP.NET application, or a winforms/wpf app that you want to use the ASP.NET Cache class with? If the former, then yes, passing the global HttpContext.Current.Cache is the right thing.

Roman Over a year ago

Worked :) I did pass the HttpContext.Current.Cache and it works great. thanks :)

kerrubin · Accepted Answer · 2011-01-03 15:42:07Z

I have done almost the same things, but with a different code (and it work for me) : (CacheKeys is an enum)

using System;
using System.Configuration;
using System.Web;
using System.IO;
    public static void SetCacheValue<T>(CacheKeys key, T value)
    {
        RemoveCacheItem(key);
        HttpRuntime.Cache.Insert(key.ToString(), value, null,
            DateTime.UtcNow.AddYears(1),
            System.Web.Caching.Cache.NoSlidingExpiration);
    }
    public static void SetCacheValue<T>(CacheKeys key, T value, DateTime expiration)
    {
        HttpRuntime.Cache.Insert(key.ToString(), value, null,
            expiration,
            System.Web.Caching.Cache.NoSlidingExpiration);
    }
    public static void SetCacheValue<T>(CacheKeys key, T value, TimeSpan slidingExpiration)
    {
        HttpRuntime.Cache.Insert(key.ToString(), value, null,
            System.Web.Caching.Cache.NoAbsoluteExpiration,
            slidingExpiration);
    }
    public static T GetCacheValue<T>(CacheKeys key)
    {
        try
        {
            T value = (T)HttpRuntime.Cache.Get(key.ToString());

            if (value == null)
                return default(T);
            else
                return value;
        }
        catch (NullReferenceException)
        {
            return default(T);
        }
    }

Collectives™ on Stack Overflow

ASP.NET Object Caching in a Class

3 Answers 3

4 Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related