How to make downloadable links?

budncal

I've been coding for several years, but only recently have I found myself in a situation where I need to make a file download automatically when you click on its link. I realized I have no idea how to do this with PHP. Can anyone give me some direction? This is a project for the microscopy department of a college to make their images downloadable. The web pages show thumbnails and descriptions of the images, and I need to make a link that would download the hi-rez versions upon clicking. I don't want to send them off to an FTP server, but have them download the file by just clicking the link. Does the server need to be enabled for FTP or what?
Thanks

sarahk

Judging from some of the clipart sites who all recommend you right mouse click and save as you will either need to tackle ftp or zip up the graphic and let them access that.

If you choose to zip then just create a hyperlink to the file (an image can be between the <a> tags.

theslinky

Try this:

header("Content-type: application/octet-stream");
and
header("Content-disposition: attachment; filename=filename.gif");
header("Content-length: " . filesize("filename.gif"));

// print your image

the content type is the most important. I doubt you'll need to use the disposition or length, but the content-disposition is a nice way of suggesting filenames so that when they are prompted to save, they will see "filename.gif" filled in, instead of "myscript.php?file=blah"

-sridhar

jamie_kerwick

I use

header("Content-type: application/save");

rather than octet-stream.

I found that with IE, using octet-stream didn't always prompt to save. In the particularly WORD files would still be opened within the browser.
Only application/save would force the download.

Jamie

yugo

Is it anyhow possible to detect whether the file was successfully downloaded?
I believe I found a post in php builder archives, but i'm unable to open the post.

Does anyone have a solution or a suggestion, because I'm writing a script that will count only successful downloads and block a user from dowloading the file again after that.

dannys

No, I don't think there is any way to tell how much data a user has received.

yugo

OK I got over the fact that i can't see whether the download finished or not, now i have a different kinda problem 🙂

I save the files into mysql. When a user tries to download the file i do all the necesary checking, feed him the header information and then the longblob value from mysql.

When the user clicks Save in the Save file dialog everything goes well. But if the user clicks Open for a zip file for example, he is prompted again with the same dialog. In this dialog, if he clicks Save, the file is normally saved, (the problem is here🙂 if he clicks Open again, the file downloads and opens, but it is empty (0 😎.

Any idea why and how to fix that?