Chapter 14: Caching problem

dbcook8 · October 17th, 2008, 10:26 AM

I am working on the exercise on page 512. From the Contact Us page I am able to send the original email. However, when I go back to the Contact Us page to send the second email, where caching takes place, I get a page error.

Error: SysWebForms.PageRequestManagerServerErrorException : Object reference not set to an instance of an object.

Code: 0

Any ideas on this error?

Imar · October 17th, 2008, 01:18 PM

Hi there,

Did you make any changes to the code? If so, can you post it here?

Cheers,

Imar

---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of Beginning ASP.NET 3.5 : in C# and VB, ASP.NET 2.0 Instant Results and Dreamweaver MX 2004
Want to be my colleague? Then check out this post.

dbcook8 · October 17th, 2008, 05:22 PM

The following code that I added ContactForms.acsx.cs seems to be what is causing the problem:

        if (Cache["ContactFormMailBody"] == null)
        {
            mailBody = System.IO.File.ReadAllText(fileName);
            Cache.Insert("ContactFormMailBody", mailBody, new CacheDependency(fileName));
        }
        else
        {
            mailBody = Cache["ContentFormMailBody"].ToString() + "\r\n(File from the cache)";
        }

Imar · October 18th, 2008, 04:10 AM

Hi there,

Take a look at the Cache keys you are using:

Code:

if (Cache["ContactFormMailBody"] == null)
{
  mailBody = System.IO.File.ReadAllText(fileName);
  Cache.Insert("ContactFormMailBody", mailBody, new CacheDependency(fileName));
}
else
{
  mailBody = Cache["ContentFormMailBody"].ToString() + "\r\n(File from the cache)";
}

You check for one key (ContactFormMailBody) and insert that in the cache, but then in the else block you try to access another key (ContentFormMailBody).

Hope this helps,

Imar

---------------------------------------
Imar Spaanjaars
http://Imar.Spaanjaars.Com
Everyone is unique, except for me.
Author of Beginning ASP.NET 3.5 : in C# and VB, ASP.NET 2.0 Instant Results and Dreamweaver MX 2004
Want to be my colleague? Then check out this post.

dbcook8 · October 19th, 2008, 10:46 AM

Thanks Imar. I have been a software developer for 21 years and sometimes it still takes 2 sets of eyes to find a problem. :-)