Cache object expiration

[Diffident]

Hello All,

I inserted an object into cache with absolute expiration using the following
code:

DateTime AbsoluteExpirat ionDate = DateRangesForDa taLists[0,0].AddDays(1);

//Expires the next day
Cache.Insert("D ataListStartEnd Dates",DateRang esForDataLists, null,AbsoluteEx pirationDate,Ti meSpan.Zero);

How can I know if the above cache object expired or not before accessing? Is
there any API in cache class that I could use?

Any pointers?

Thank you.

[Peter Bromberg [C# MVP]]

the simplest way to test for expiration is to check if the Cache item is null:

if Cache["DataListStartE ndDates"]==null)
{
// re-add the item here
}

You can also configure CacheItemRemove d calllback that gets fired when the
item is evicted from the Cache. the documentation at MSDN or in your local
help shows example code.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

Hello All,

I inserted an object into cache with absolute expiration using the following
code:

DateTime AbsoluteExpirat ionDate = DateRangesForDa taLists[0,0].AddDays(1);

//Expires the next day
Cache.Insert("D ataListStartEnd Dates",DateRang esForDataLists, null,AbsoluteEx pirationDate,Ti meSpan.Zero);

How can I know if the above cache object expired or not before accessing? Is
there any API in cache class that I could use?

Any pointers?

Thank you.

[Diffident]

So if the cache object's expiration has expired it is instantly set to null?

Thank you.

"Peter Bromberg [C# MVP]" wrote:

the simplest way to test for expiration is to check if the Cache item is null:

if Cache["DataListStartE ndDates"]==null)
{
// re-add the item here
}

You can also configure CacheItemRemove d calllback that gets fired when the
item is evicted from the Cache. the documentation at MSDN or in your local
help shows example code.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

Hello All,

I inserted an object into cache with absolute expiration using the following
code:

DateTime AbsoluteExpirat ionDate = DateRangesForDa taLists[0,0].AddDays(1);

//Expires the next day
Cache.Insert("D ataListStartEnd Dates",DateRang esForDataLists, null,AbsoluteEx pirationDate,Ti meSpan.Zero);

How can I know if the above cache object expired or not before accessing? Is
there any API in cache class that I could use?

Any pointers?

Thank you.

[Peter Bromberg [C# MVP]]

Diffident,
When an object in Cache expires, it is "evicted" - it's no longer there. So
if you look for it by key, you will get null.
Actually testing for null before attempting to access anything in Cache ,
Session, Application or Viewstate is a good programming practice.
Hope that helps.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

So if the cache object's expiration has expired it is instantly set to null?

Thank you.

"Peter Bromberg [C# MVP]" wrote:

the simplest way to test for expiration is to check if the Cache item is null:

if Cache["DataListStartE ndDates"]==null)
{
// re-add the item here
}

You can also configure CacheItemRemove d calllback that gets fired when the
item is evicted from the Cache. the documentation at MSDN or in your local
help shows example code.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

Hello All,

I inserted an object into cache with absolute expiration using the following
code:

DateTime AbsoluteExpirat ionDate = DateRangesForDa taLists[0,0].AddDays(1);

//Expires the next day
Cache.Insert("D ataListStartEnd Dates",DateRang esForDataLists, null,AbsoluteEx pirationDate,Ti meSpan.Zero);

How can I know if the above cache object expired or not before accessing? Is
there any API in cache class that I could use?

Any pointers?

Thank you.

[Diffident]

Thank you!! That helped.

"Peter Bromberg [C# MVP]" wrote:

Diffident,
When an object in Cache expires, it is "evicted" - it's no longer there. So
if you look for it by key, you will get null.
Actually testing for null before attempting to access anything in Cache ,
Session, Application or Viewstate is a good programming practice.
Hope that helps.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

So if the cache object's expiration has expired it is instantly set to null?

Thank you.

"Peter Bromberg [C# MVP]" wrote:

the simplest way to test for expiration is to check if the Cache item is null:

if Cache["DataListStartE ndDates"]==null)
{
// re-add the item here
}

You can also configure CacheItemRemove d calllback that gets fired when the
item is evicted from the Cache. the documentation at MSDN or in your local
help shows example code.
Peter
--
Co-founder, Eggheadcafe.com developer portal:
http://www.eggheadcafe.com
UnBlog:
http://petesbloggerama.blogspot.com


"Diffident" wrote:

> Hello All,
>
> I inserted an object into cache with absolute expiration using the following
> code:
>
> DateTime AbsoluteExpirat ionDate = DateRangesForDa taLists[0,0].AddDays(1);
>
> //Expires the next day
> Cache.Insert("D ataListStartEnd Dates",DateRang esForDataLists, null,AbsoluteEx pirationDate,Ti meSpan.Zero);
>
> How can I know if the above cache object expired or not before accessing? Is
> there any API in cache class that I could use?
>
> Any pointers?
>
> Thank you.