Stupid Caching question

[Chris]

I periodically, once every week or so, get an error when trying to read an
XML doc stored in cache. I get an 'object not set to a reference' I have a
gut feeling it happens when the app is under strain and the moment between
testing the cache and returning the cached xml doc it expires. I have read
several other people have the same problem. I have seen some C# code which
theoretically makes sense to me, but I don't understand the syntax and how
you would write it in VB.net. And I thought I had got me head round
"converting" C# ....... Can anyone explain it. I have tried:

Dim cacheitem as object = Cache(key) as XMLDocument

but with no luck. Here is the C# code in full.


Object cacheItem = Cache[key] as DataTable;
if(cacheItem == null)
{
cacheItem = GetData();
Cache.Insert(key, cacheItem, null, DateTime.Now.AddHours(1),
TimeSpan.Zero);
}
return (DataTable)cacheItem;

Regards, Chris.

 

[Alvin Bruney [MVP]]

You know implicitly that the object is a datatable, you don't need to
*download* it into a type of object and then cast the return type to a
datatable, just use a datatable, it will avoid the conversion hit and make
the code more readable.

Dim cacheItem As Object = TryCast(Cache(key), DataTable)

If cacheItem Is Nothing Then

cacheItem = GetData()

Cache.Insert(key, cacheItem, Nothing, DateTime.Now.AddHours(1),
TimeSpan.Zero)

End If

Return CType(cacheItem, DataTable)


--
Regards,
Alvin Bruney
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