php: empty line from nowhere

Question

I have strange error and not sure how to tackle it without wasting too much time. I have a method in my controller which should return xml using:

  header("Content-type: text/xml");
  header("Content-Disposition: attachment; filename=output.xml");
  header("Pragma: no-cache");
  header("Expires: 0");

the thing is that the output is not valid xml because of empty line and I have no idea from where it comes, do you have an idea how to fix this? maybe ignore this empty line or something? I do not want to debug the whole framework... I tried to use var_dump(debug_backtrace()) but I get one big mess probably because of doctrine.

Answer 1

Almost always, there will be an empty line before or after your <?php ?> tags. If not in your main file, look at your includes.

Also, a little tip... if your file is pure PHP, just start it with <?php and never close the PHP tag. Closing it isn't necessary, and then you avoid blank lines at the end causing you trouble.

Answer 2

Use ob_clean() which clears buffer that had unwanted newline

Answer 3

Also, any error messages will be printed into the document before the headers. but sometimes it's hard to find the offender when there's no error. Try this:

ob_start()

Put that first thing in your script, this will ensure that nothing else is output until you call

ob_flush()

Which may not be necessary for you (the ob_flush).

Also, I had this issue a while ago where a script that was included in the middle of another script had a single character after the closing php tag, which caused that single character to push the headers down and make the response invalid.

So I would follow the suggestion made by Brad that you don't use closing php tags unless you have to.

Answer 4

I run into this issue from time to time. And it can be very frustrating. :-) Either way - I find this helpful. This will show files with an empty line followed by a php start tag. It will show false positives but helps narrow the search down nicely.

pcregrep -Mron '\n\<\?php' .

Answer 5

I had the same issue and the problem came from a blank line after a closing ?> at the end of one of my php files.

Double check all your php files and remove the closing ?>