PHP File Download using POST data via jQuery AJAX

Question

So I know there have been a number of similar posts, but I think this is enough of a variation to warrant its own question:

I am building an XLS exporter in PHP and jQuery. I am trying to POST an array with jQuery (which I believe is going to be too long as a GET querystring), and use it to generate an XLS file on my server, which the user can then download.

I have used hidden iframes in the past to accomplish this, but since they just redirect to a url, this requires me to use GET, which makes me nervous.

My question is then: how do I store those files on my server and link to them if they're being generated dynamically, potentially by multiple users? Would a hidden iframe link to a separate PHP script that locates THEIR file based on a session ID or something like that?

Thanks in advance for any guidance here on what I'm sure gets asked all the time :)

Answer 1

It is possible to POST to a hidden iframe. Therefore, you don't need to worry about the length of the query string; you will post the key/value pairs which will generate your XLS file and subsequently force the file download to the browser.

<form method="post" action="/download/xls" target="download_xls"> 
  <fieldset>
    <label>Key 1:</label>
    <input type="text" name="key_1" />
  </fieldset>

  <fieldset>
    <label>Key 2:</label>
    <input type="text" name="key_2" />
  </fieldset>

    <fieldset>
            <input type="submit" value="Submit" /> 
    </fieldset> 
</form>

<iframe id="download_xls" name="download_xls" width="0" height="0" scrolling="no" frameborder="0"></iframe>

UPDATE A quick Google search turned up this article: http://particletree.com/notebook/ajax-file-download-or-not/

Basically, the suggestion is to POST your form to the current page and respond with a file download. This alternative might be good enough for you.

Answer 2

This seems like it should be pretty simple, but it all depends on where you're putting those XLS files you're generating. If you're intending that the response to the post should be a "Save File" dialog — that is, the file itself — then all you have to do is make sure the "Content-Disposition" header is set to "attachment", and then stream out the file contents.

If you're going to generate the file and keep it around, well you're going to have to store it somewhere with an identifier. In that case, you'd just respond with an ordinary page that's got a "download" link, such that that link includes the file identifier. That can trigger either a GET or a POST, and the server would respond to that pretty much as I described above.

A hidden <iframe> doesn't really figure into this, in my opinion.