Re: implementing downloads with php?

On Apr 2, 2015, at 7:55 PM, Sean Greenslade wrote:

On Thu, Apr 02, 2015 at 07:01:59PM -0700, Jeffry Killen wrote:

On Apr 2, 2015, at 6:33 PM, Sean Greenslade wrote:

A quick google turned up this result: http://stackoverflow.com/questions/8485886/force-file-download-with-php-using-header See if that helps. --Sean

Thank you for the link, I am getting an idea of what is going on here, even though I don't know that the posters problem was solved. So, if I understand the basics, a bunch of headers are sent and then the file is read. But I don't see a print or echo statement in any of the code in the related posts.

The header set functions need to be run before the actual content of the page is generated. This has to do with the way that the HTTP protocol works. The header is always generated by the webserver, and PHP has the option of modifying / appending to it before it gets sent. This all must happen before the content of the page gets sent, becase the server must finish and send the headers before it sends any content. Once there is content, the headers are locked for that pageload.

I have read a file as a string, sent a Content-Type header and then used a print statement to send the file contents for an async request: in cases where css or javascript is requested after a page loads. The output is sent to the browser.

I'm a bit confused by this, so you'll need to clarify. Setting the headers to inform the browser that the file is a download has nothing to do with js, css, or html. It's a built-in feature of the browser to interpret the headers and decide to download the file instead of display it. All you need to take advantage of this is to place a link to the PHP page that supplies the file and let the user click it. If the page sets the headers correctly, clicking that link will cause thier browser to start downloading the file (and, depending on browser settings, possibly offer a save location dialog). If you're attempting to achieve this using an ajax solution, I'd actually recommend not trying to load the file by ajax. Just use javascript to open a new window to the download link. Using the same mechanism as above, the browser will handle things for you.

No I wasn't intending to use ajax per-se. I was just using that as a parallel to illustrate using a print statement to actually send the file contents. Is it necessary to call print or echo here? I would print a directory listing of a directory containing downloadable files to the browser with php, where each file listing is wrapped in an anchor that has the href value set to a script with a query attached: something along the lines of <a href="downloader.php?file=[file to download]">[file to download]</a> I am thinking of any file type: .pdf, .rtf, .swf, .doc, mpg, mpeg, mp3, binary, as well as plain text, whatever

But this situation appears different. The file content is sent to the browser but the browser writes it directly to a separate file (?) JK

Note that there is no way to specify where the file gets downloaded. That is up to the browser, and based on its settings. Some browsers default to asking you where to save the file, and others toss all files into a Downloads directory. --Sean

Yes, the destination is generally set as a browser preference by the user. I often get a dialog ( on Mac OSX, Firefox and others) asking me if I want to open the file, or save it IF it is a pdf file. Otherwise it just appears in an "httpDownloads" folder my desktop according to my preference setting. JK