how use caching in asp.net mvc3?

Question

I have problem with cache in my asp.net mvc3 application.

My code

using System.Web.Caching;
...
class RegularCacheProvider : ICacheProvider
{
    Cache cache ;

    public object Get(string name)
    {
        return cache[name];
    }

    public void Set(string name, object value)
    {
        cache.Insert(name, value);
    }

    public void Unset(string name)
    {
        cache.Remove(name);
    }
}

And I use singleton for give value for it :

School schoolSettings = (School)CacheProviderFactory.Cache.Get("SchoolSettings");
            if (schoolSettings == null)
            {
                CacheProviderFactory.Cache.Set("SchoolSettings", someObject);
            }

So in first use it does not work and give me an error cache[name] is null.

What I'm doing wrong?

Any help would be appreciated.

Were you planning on assigning a value to cache at some point? 'cos you haven't. — Marc Gravell
– Marc Gravell, Commented Aug 7, 2012 at 12:58
Also, you claim cache is a singleton and that there is a CacheProviderFactory.Cache - neither of these things are shown in the code. You are asking us to guess what you have removed; that will not lead to a good answer... — Marc Gravell
– Marc Gravell, Commented Aug 7, 2012 at 13:00
Slightly off topic but you might want to look at using dependency injection to provide the cache instance. That way you can change it to another caching provider if needed and you can also unit test easier. — mbx-mbx
– mbx-mbx, Commented Aug 7, 2012 at 13:02

Marc Gravell · Accepted Answer · 2012-08-07 13:01:27Z

2

At no point have you given cache a value... and note that the regular web cache probably isn't your best bet if you want it separate; perhaps

MemoryCache cache = new MemoryCache();

answered Aug 7, 2012 at 13:01

Marc Gravell

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1 Comment

Mateusz Rogulski Over a year ago

I have had the same problem - problem with null reference. But I have change it for HttpRuntime.Cache

Mark Oreta · Accepted Answer · 2012-08-07 12:56:25Z

1

What about using the HttpRuntime.Cache, this example would cache for an hour?

HttpRuntime.Cache.Add("SchoolSettings", someObject, null, DateTime.Now.AddHours(1),
                       System.Web.Caching.Cache.NoSlidingExpiration,
                       System.Web.Caching.CacheItemPriority.Normal, null);

answered Aug 7, 2012 at 12:56

Mark Oreta

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3 Comments

Mateusz Rogulski Over a year ago

I need to use System.Web.Caching

Marc Gravell Over a year ago

@MateuszRogulski why is that? this is a private implementation detail; frankly it shouldn't matter how it is implemented

Mateusz Rogulski Over a year ago

Well, I have change it with your method. Thanks :)

Allen Wang · Accepted Answer · 2012-08-07 15:04:48Z

Try the following code. it works fine for my project

 using System.Runtime.Caching;

    public class RegularCacheProvider : ICacheProvider
        {
            private ObjectCache Cache { get { return MemoryCache.Default; } }

            object ICacheProvider.Get(string key)
            {
                return Cache[key];
            }

            void ICacheProvider.Set(string key, object data, int cacheTime = 30)
            {
                var policy = new CacheItemPolicy {AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(cacheTime)};
                Cache.Add(new CacheItem(key, data), policy);
            }

            void ICacheProvider.Unset(string key)
            {
                Cache.Remove(key);
            }
        }

Hector Correa · Accepted Answer · 2012-08-07 13:01:35Z

0

Change the code where you check for the value as follow:

School schoolSettings = CacheProviderFactory.Cache.Get("SchoolSettings") as (School);

Notice that I am using "as" rather than casting the object. Cast will blow up if the value is null while "as" will just give you a null value which is what you expect.

answered Aug 7, 2012 at 13:01

Hector Correa

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1 Comment

Hector Correa Over a year ago

Like Marc Gravel mentioned, Are you sure cache is not null by the time the Get method is called?

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