prefend loading from temporary file

rikblank

Hi,
I generate a csv file from a query. This file is generated on the server and then the users can download this file. The filename is their session id.

Then when the submit a new query the file on the server is changed but people still download the same file because the local temp. file will be download. How can I prefend this to happen? It's caused because the sessionid and thus the filename is the same. it's no option to change this.

Anyone know how?

Regards,
Rik

factory21

The file is being cached. If your users are downloading the file directly via URL, then you're pretty much stuck. There may be a few webserver options to set the file to expire/not be cached.

An alternate way to prevent caching is to download the file via a script such as PHP. This gives you control over most of the headers and in general, the output of scripts is not cached. Such is script should be pretty easy, the thing to pay a little attention to is to set the correct MIME content type. Otherwise, it's just a matter of opening a file and printing its contents to the stdout.

rikblank

Yes you're right and thanks for your comment. I've thought about that but the script is included from another file, meaning the headers are already sent to the browser. I think I should change this and let it load at the begin of the include file and sent my own headers. Or do you have another idea?
Thanks again.

Regards,
Rik

rrijnders

How are the users downloading the file? Are they clicking a link that you provide directly to the file? Are they clicking a link that you provide to a script that uses passthru()? How they download the file will determine the possible remedies for your problem.

In most cases, even if you are linking directly to the csv file, you can fool the browser into not chaching by changing the URL slightly. For example, if you generate a link to the csv file like so:
<b>
<A HREF="theFile.csv">download!</A>
</b>
Then you can change the url slightly:
<b>
<A HREF="theFile.csv?x=9">download!</A>
</b>
The request variable appended to the end can be changed each time they create a new file. This should be easy to increment since you say that sessions are already active. The browser will see this "unique" url as a link to a different file and, thus, not return the cached version of the csv file.

HTH
-- Rich Rijnders
-- Irvine, CA US

factory21

As long as your main php document hasn't sent any data to the output stream, you can set headers in your included file.