xajax response begins with a blank line

Question

On my system (running PHP 5.3.15, Apache 2.2.22) xajax works fine. On another system running PHP 5.2.17, Apache 2.2.22), xajax responses are preceded by a blank line. This can be seen in the Firebug Network tab, XHR->Response. There's literally a blank line before

<?xml version="1.0" encoding="utf-8" ?>

What on earth could be causing this and how can I fix it?

Having a blank line before the start of an XML document is an error and leads to the error

Error: XML or text declaration not at start of entity

in the Browser's Error console.

Look through your PHP includes for a blank line before the opening ` — Michael Berkowski, Dec 06 '12 at 02:15
Also look for a blank line following the closing `?>` in any includes run before the XML output. — Michael Berkowski, Dec 06 '12 at 02:18
@MichaelBerkowski it must be something like this - in fact, when I do a view source on the page, it has a blank line before the . Perhaps that's causing it. — Scott C Wilson, Dec 06 '12 at 02:28
Yep that's almost certainly the cause then. You'll just need to go through all your includes and clean the whitespace outside the `` — Michael Berkowski, Dec 06 '12 at 02:30
Please convert your comment into an answer so I can give you points. — Scott C Wilson, Dec 06 '12 at 02:47

score 1 · Accepted Answer · answered Dec 06 '12 at 02:49

1

Look through all the PHP includes which are executed before your expected XML output. It is likely that one or more of them has an errant line break either before the opening <?php or following the closing ?>, which gets passed to the browser as output before the XML header.

      <-- Line break
<?php

?>
      <-- Line break

If you are on a UNIX-like system, you can use head to examine the first line or tail to examine the last line of each file. Look for the file that doesn't begin or end with <?php / ?>

# In a directory of PHP files...
head -n1 *.php
tail -n1 *.php

answered Dec 06 '12 at 02:49

Michael Berkowski

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This was exactly the issue - someone had accidentally edited one of the includes and added a blank line after what should have been the end. It's interesting that some coding standards (Such as JetBrains's Code Inspector in PHP Storm) encourage you *not* to specify the closing "?>" to avoid this very problem. Is there a php flag I could have used to let the interpreter find this problem? – Scott C Wilson Dec 06 '12 at 02:59
@ScottWilson I'm not aware of any such flag. Some people use a commit hook in version control to trim whitespace. – Michael Berkowski Dec 06 '12 at 03:03

xajax response begins with a blank line

1 Answers1