在流文件或来自ifram的HTTP标头之前返回JSON？

Question

I have a form that uses a hidden iframe to submit a file to a script that changes the file and then returns the changed file. I found that I don't actually have to save the file anywhere if I just do something along the lines of echo file_get_contents(tmp); , where tmp is the path of the file uploaded to the apache tmp directory.

The script also does: header("Content-type: application/octet-stream") so that when the iframe loads, the user is prompted for download. I would like to know, on the client side, if everything went alright with the server. It's not an XMLHttpRequest, so I can't check the headers, and the only thing returned is the file itself.

Is there some way to return some json before streaming the file? Or, is there a way to check the headers of an iframe?

Currently, I've been setting a cookie with the server and checking every half a second with javascript to see if the cookie was set. I would prefer a less hacky solution than this though.

Answer 1

If you stream JSON before the file, the MIME header will be invalid and the browser will not be able to download the file.

In terms of checking "if everything went alright with the server", why wouldn't you be determining this on the server , rather than going round-trip to the client and back again? Allowing it to error-out on the client smells of bad design.