Re: offering downloads of blobs (mysql) with php

  • From: Alex Hall <mehgcap@xxxxxxxxx>
  • To: programmingblind@xxxxxxxxxxxxx
  • Date: Sat, 30 Apr 2011 12:08:01 -0400

Thanks. Your script says to use readfile, but I have a blob, not a
file, so the few tutorials I have found say to echo the blob's
content. When I do that, though, I get the same result you would get
if you opened a zip file (my tests are all on zip files) with notepad;
mostly nothing readable. I have hard-coded the type to be
"application/zip" since I can't find a way to make php guess the mime
type from the file name, but I still get no download, just all that
gibberish text printed to the page. Readfile() does nothing, as I
expected since this is not actually a file, just the file's binary
data. Below is my script. Let me know if it does not come out right.

<?php
include('php/common.php');
if(isset($_GET['id'])){
 $id=$_GET['id'];
 $con=dbConnect()
  or die("The file you requested could not be retrieved because the
database appears to be down. Please try again later.");
 $sql='select m.filename, m.filesize, m.type, m.content, p.title from
media m, podcasts p where m.podcast='.$id.' and p.podcast_id='.$id;
 //echo $sql.'<br>';
 $res=mysql_query($sql)
  or die(heading(1, 'Error').'<p>There was a problem finding the file
you requested. Please try again later.</p><p>'.mysql_error().'</p>');
 $title=mysql_result($res, 0, 'title');
 $size=mysql_result($res, 0, 'filesize');
 $filename=mysql_result($res, 0, 'filename');
 $type=mysql_result($res, 0, 'type');
 $content=mysql_result($res, 0, 'content');
 //echo $title.' (title), '.$filename.' (file name), '.$size.' bytes,
type='.$type.'<br><br>';
 header('HTTP/1.1 200 OK', True, 200);
 header('Content-Description: File Transfer');
 header('Content-Type: '.$type);
 header('Content-Disposition: attachment; filename='.$filename);
 header('Content-Transfer-Encoding: binary');
 header('Expires: 0');
 header('Pragma: public');
 header('Content-Length: ' .$size);
 readfile($content);
 exit;
}
else{ //error out; no file to download
?>

<html>
<head>
<title>No File to Download</title>
</head>

<body>
<?php
include_once('php/nav.php');
echo heading(1, 'No File Selected');
echo '<p>Please select a file; this page will only work if given a
valid file number to retrieve.</p>';
?>
</body>
</html>
<?php } ?>

On 4/30/11, Jacob Kruger <jacobk@xxxxxxxxxxxxxx> wrote:
> That would generally be related to redirecting content from another source,
> so it wants to change the file/content type that the browser is expecting as
> such.
>
> For example, the one thing I have is checking if someone is logged in to a
> site, before sending them a word document directly from a PHP script - idea
> is partly so they wouldn't be able to know/see the actual file path/URL, but
> the PHP script tells the browser it's receiving a word document, and then
> passes it through to the browser:
>
> $PhysicalFileName = "cnsttn/constitution.doc";
> header('HTTP/1.1 200 OK', True, 200);
> header('Content-Description: File Transfer');
> header('Content-Type: application/msword');
> header('Content-Disposition: attachment; filename="constitution.doc"');
> header('Content-Transfer-Encoding: binary');
> header('Expires: 0');
> header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
> header('Pragma: public');
> header('Content-Length: ' . filesize($PhysicalFileName));
>
> // readfile() will simply pass the file from the drive straight to the
> client.
> readfile($PhysicalFileName);
> exit;
> //that last statement closes the browser/server transaction/communication as
> such
>
>
> Jacob Kruger
> Blind Biker
> Skype: BlindZA
> '...fate had broken his body, but not his spirit...'
>
> ----- Original Message -----
> From: "Alex Hall" <mehgcap@xxxxxxxxx>
> To: "programmingblind" <programmingblind@xxxxxxxxxxxxx>
> Sent: Saturday, April 30, 2011 2:34 AM
> Subject: offering downloads of blobs (mysql) with php
>
>
>> Hi all,
>> I have a database project due next Wednesday. It is done, but I am
>> adding things since I have the time (and I really don't want to do my
>> calc homework right now). One of my databases is for podcasts, the
>> other for articles. The articles one is fine; I can serve that content
>> since it is stored in a longtext field, so I need only echo it to the
>> page. The podcast table is different, though. I looked up this stuff
>> already, but was taken to a script that was using a header() function
>> (php) and giving it mime information about the file, then it echoed
>> the blob, and that was it. I am wondering:
>> 1. What is all this mime stuff about?
>> 2. My only experience with files and webpages is putting a link to a
>> file, even a binary one, and letting the browser take care of it. Why,
>> then, did the script I found echo the blob and leave it at that? It
>> was not generating an html page with a link; the link was to
>> download.php, and download.php was the one doing all this with the
>> mime information and the echoing of the blob.
>> 3. Does anyone know of a good resource to find out more about serving
>> blobs so users can download them? Most of what I find is about
>> displaying images stored as blobs, but I want to offer a download link
>> for a given podcast's media file.
>> Thanks in advance.
>>
>> --
>> Have a great day,
>> Alex (msg sent from GMail website)
>> mehgcap@xxxxxxxxx; http://www.facebook.com/mehgcap
>> __________
>> View the list's information and change your settings at
>> //www.freelists.org/list/programmingblind
>>
>
> __________
> View the list's information and change your settings at
> //www.freelists.org/list/programmingblind
>
>


-- 
Have a great day,
Alex (msg sent from GMail website)
mehgcap@xxxxxxxxx; http://www.facebook.com/mehgcap
__________
View the list's information and change your settings at 
//www.freelists.org/list/programmingblind

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