Saving integer in cache

andreas5 · September 18th, 2010, 05:32 AM

Hi, just finished chapter 16 in Imars awesome book and i want to implement caching to my own little project.

I am counting the number of pictures assosiated with a tag, and i want to save the number in my cache. But i am unsure of how to check if the item is in the cache already.

I wanted to use TryCast(and then check for Nothing) but it did not work with Integers :s

Code:

            Dim count As Int32 = Nothing
            count = Cache(TagN + "Count")
            If count = Nothing Then
                count = (From ccc In myEnt.TagLinks
                        Where ccc.Tag.TagName = TagN
                        Select ccc).Count

                Cache.Insert(TagN + "Count", count, Nothing, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(10))

            End If

How should i do this? Are there other things in this code snippet i should change?

Imar · September 19th, 2010, 07:57 AM

Hi there,

TryCast only works with reference types as it returns Nothing when the conversion fails. Try this code instead:

Code:

 
Dim count As Int32
Dim cachedCount As Object = Cache("Count")
If cachedCount Is Nothing Then
  count = 23
  Cache.Insert("Count", count, Nothing, System.Web.Caching.Cache.NoAbsoluteExpiration, TimeSpan.FromMinutes(10))
Else
  count = CType(cachedCount, Int32)
End If

This code checks if the cached item is Nothing (using Is, not =). If it is, it assigns some value and stores the item in the cache. If the item does exist, it's casted to an Integer using CType.

Hope this helps,

Imar