File Downloads

[Anon]

Hi.

This maybe a beginners question,
but i still need help on this:

How is it possible to initiate a
download from a PHP script ?

In detail:
I have generated a PDF file.
If one clicks at the link to this file,
it will be displayed inside the browser
(if plugin exists).

But i want it to be downloaded, not
displayed.

Any idea ??

Greetings
Tam

[Anon]

You're right, you're not the first to face this problem. With NS, just put these lines before returning the file and it'll work :

Header("Content-Type: application/octet-stream");
Header("Content-Disposition: attachment; filename=$filename");

With some versions of IE, this doesn't work; the browser "sniffs" the data, finds it's PDF and opens it instead of prompting the "Save as" dialog box. In theses cases, you have to change the Content-Type to application/unknown, for instance (disables data-sniffing) and remove the filename=$filename part (IE would use the .pdf extension to guess the format). Annoying, isn't it ? This wonderful Microsoft feature is supposed to make users' life easier :-(

[Anon]

Thank you for this,
but i am really new to PHP and
always get an error when trying
to send headers.

Could u please give me an example ?

~Tam

[Anon]

Generally you face a problem with all file types, which the browser wants to 'view' or load into a plugin.

I usually ask my users to shift-click or right-click on the link to download it. This functionality might be obtained through some clientside JavaScript. I haven't seen examples or tried developing anything myself, but it could be a way to go.

Martin

[Anon]

Martin wrote:

I usually ask my users to shift-click or right-click on the link to download it. This functionality might be obtained through some clientside JavaScript.

Are you sure ? Reminds me nothing... If it really exists, I'd be glad to know.

[Anon]

Headers can only be sent <i>before</i> any data has been output. It includes any space or line feed, so be sure to remove them before your <?php ?> PHP section. The general scheme to output a PDF file is as follows :

//Make the PDF if dynamic
$fp = fopen("test.pdf", "w");
$pdf = pdf_open($fp);
...
pdf_close($pdf);
fclose($fp);

//Headers (no data has been output yet)
Header("Content-type: ...");
Header("Content-disposition: ...");
//Content-length is mandatory if you want to use plug-in; not the case here, just for info
Header("Content-length: ".filesize("test.pdf"));

//Output file
readfile("test.pdf");

//Remove file if it was generated
unlink("test.pdf");

That's all...

[Anon]

Thanks a lot !

This works fine, with one thing:
When it prompts for the download,
it gives the name of the PHP file.

Any idea to avoid that ?
Or is this a IE-thing ?

[Anon]

Then adjust the $filename variable in Olivier's code.

[Anon]

I did, as you can see :

<pre>
--snip--

<script language="PHP">
$file = "../data/woche2.pdf";
Header("Content-Type: application/octet-stream");
Header("Content-Disposition: attachment; filename=\"woche2.pdf\"");
readfile($file);
</script>

--snip--
</pre>

~Tam

[Anon]

Don't put any " around the filename.
Und das wird perfekt sein ;-)

[Anon]

Olivier,

I don't know whether it could be done from JavaScript, but my thought was that so much can be done this way, and forcing a download could be one of them. Just a guess...

Martin

[Anon]

OK Folks,

here is a solution i got from this
discussion.

~Tam

<pre>
--snip--

<script language="PHP">
// Start an buffer-object to prevent output BEFORE sending headers
ob_start();

// get the environment: Querystring
$qstring = explode("&",getenv("QUERY_STRING"));

// split 1st parameter into $command and $file
list($command,$file) = split("=", $qstring[0]);

// if the $command was "send" then send the $file
if ( strcmp($command,"send")==0)
{
// get the Filename without path
$fn = basename($file);
// Set the Content-Type
Header("Content-Type: application/octet-stream");
// Set the filename the user should be prompted for download
Header("Content-Disposition: attachment; filename=$fn");
// read and stream the file to the user
readfile($file);
// exit the programm
exit();
}
else
{
// proceed the side here
}

</script>

-- snip--
</pre>

[Anon]

Some remarks :

• Is it necessary to call ob_start() ? Normally it's not. This function was not even available in PHP3.

• Is there a particular reason to parse the QUERY_STRING as you do ? PHP automatically creates variables from it. With a "send=file" QUERY_STRING, the variable $send with value "file" is created. Your code could look like this :

<?php
if(isset($send))
{
$fn = basename($send);
...
readfile($send);
exit();
}
...
?>

• To test string equality, just use == operator, strcmp is not necessary (you're a C coder, aren't you ?)

[Anon]

Yes, i am a C coder :-)

And i got some problems without 'ob_start()':
It says startet output before sending header.
But this may have another reason: the original page where i use that code is much bigger.

Regarding that QuersString stuff: I didn't know that method...

~Tam

Have a Happy new Year folks...

[Anon]

PHP automatically creates variables for GET, POST, Cookies, environment variables... A dream for a C coder !

Regarding ob_start(), it only prevents the error message, but doesn't correct the problem. If you output something between ob_start() and readfile(), it will be buffered, as well as the PDF file itself. When the script ends, everything is flushed, and you get additional data at the beginning of your file ! Have you checked that you could open your PDF after downloading ? Would surprise me a lot...
Therefore, you have to find the source of the problem and fix it. Shouldn't be difficult, the PHP error message gives you the line where output began. You can also view the source of the page in your browser, you'll immediately see what's before the message.