WP redirects confuse IE

Some users were having problems on a community site that was implemented using WordPress+BuddyPress. After some testing the issue involved users visiting the site with Internet Explorer (IE). These users were receiving error pages instead of site content. Other web browsers did not have similar issues.

The cause of the problem turns out to be a confluence of issues:

  • The site is hosted on a Windows+IIS server, a rare platform for WordPress (and even more so for BuddyPress) and one that probably doesn’t receive full attention during quality assurance testing.
  • How WordPress performs redirects on IIS is a bit quirky. BuddyPress issues a lot of redirects so this redirect quirk comes into play quite often. The issue is that when WordPress needs to perform a redirect on IIS it returns a “refresh” header pointing to the new page rather than a “location” header.
  • IE’s attempt to make the Internet more friendly; specifically IE’s use of “friendly error pages.” These friendly error pages replace the content delivered by the server (if that content falls below a certain size in KB).

Normally none of these issue are a problem by themselves and a web browser (including IE) will load the page indicated by the redirect. However, all three of the above issues taken together result in a situation where IE never sees the header refresh and so doesn’t redirect the user to the correct location.

The fix is fairly simple: change the headers that WordPress sends to include the standard “location” header. To do this you modify wordpress/wp-includes/pluggable.php@wp_redirect() so that it reads as follows (line 14 is new):

function wp_redirect($location, $status = 302) {
	global $is_IIS;

	$location = apply_filters('wp_redirect', $location, $status);
	$status = apply_filters('wp_redirect_status', $status, $location);

	if ( !$location ) // allows the wp_redirect filter to cancel a redirect
		return false;

	$location = wp_sanitize_redirect($location);

	if ( $is_IIS ) {
		header("Refresh: 0;url=$location");
		header("Location: $location", true, $status);
	} else {
		if ( php_sapi_name() != 'cgi-fcgi' )
			status_header($status); // This causes problems on IIS and some FastCGI setups
		header("Location: $location", true, $status);

Integrating calculated fields and model data in CakePHP

(This is mostly a summary of Dealing with calculated fields in CakePHP’s find().)

One of the great things about CakePHP is that if it doesn’t have some core functionality you want/need there are easy ways to add it. More and more I’m taking advantage of this ability. This all comes about because I wanted to have calculated fields available inline with the model data. By calculated fields I mean results that are not data columns (e.g. SELECT *, CURDATE() AS current_date FROM users … yes, that’s a fairly contrived example).

By default Cake places results from calculated fields outside the model data, like this:

    [0] => Array
            [User] => Array
                    [id] => 1
                    [username] => aaas

            [0] => Array
                    [current_date] => '2011-05-13'


What we want is to place the “current_date” calculated field inside the User model, so it’s more naturally accessed with $users[0]['User']['current_date'] instead of $users[0]['User'][0]['current_date']. Easy enough to do through a model’s afterFind() callback method (to make it widely available place the function in app_model.php).

function afterFind($results, $primary=false) {
	if($primary == true) {
		if(Set::check($results, '0.0') && Set::check($results, "0." . $this->alias)) {
			$fields = array_keys( $results[0][0] );
			foreach($results as $key=>$value) {
				foreach( $fields as $fieldName ) {
					$results[$key][$this->alias][$fieldName] = $value[0][$fieldName];
	return $results;

And yet, even as I add such enhanced functionality to my web apps I’m finding limits. The above logic is complicated a little because you don’t know what type of results you’re getting. The results you get from calling, for example, find('all') versus find('count') are not the same. But Cake doesn’t give any hints to the afterFind() callback, and as a result additional logic is included to try and guess at our data structure. The above adds a quick but incomplete hack by a) checking that the results are for the primary model queried (e.g. not from contained model), b) checking for the presence of nested numerical keys, and c) checking that there is model data to integrate with.

The take away is that while the code produces the desired data structure, in its current form it does so only for specific results.

Align two columns in Excel

I recently had two sets of data, one a full list of records and the other a list of identifiers for the records that needed to be extracted. Extracting the relevant records from the full list would be a fairly easy programming task, but the data was in Excel and I wanted to try and accomplish the task in that environment. Thankfully this problem has already been solved and the answer posted to the web.

If I have one column of identifiers for the records that need to be extracted (column A, 100 records) and one column with the full list of identifiers (column B, 1000 records) the following formula will indicate which identifiers from column B match an identifier from column A:


Just place the formula in its own column and copy down for the length of the full data set. The columns do not need to be in any particular order and you can create a separate worksheet that contains your filter list, keeping your data and your filter separate. You can then AutoFilter on your search column to see the results (and copy/paste to another worksheet if necessary).

What file was that in?

One of the more annoying things about coding is finding the right file. Or, even worse, finding a file you didn’t know you needed to look at. Especially when the number of files you’re parsing is in the thousands. If you’re on Windows the built-in search can help, but you never know if all the files in the target directory have been indexed.

Luckily, one of the nice things about coding is that you’re often dealing with plain text files. And you are typically searching for a particular string. As they say, there’s an app for that. Both *nix and Windows are capable of searching through the contents an entire hierarchy of files using command-line programs. Each OS has a variety of commands that can do the job, but I’ll highlight the two I use most often here.

In Windows you would use findstr.exe, and it’s as simple as running the following from the containing directory:

findstr.exe /MIS "searchtext" filetype

On *nix systems the grep command is your friend:

grep -lr "searchtext" filetype

Of course, a quick google search will get you all the help you need in refining your search.

Update 2012-08-22: What file wasn’t that in?

I recently had a need to find files that did not contain a specific string. A bit more difficult of a prospect. I suspect there’s probably a way to do this on the command line, but so far I’ve only come up with a work-around (in Windows). Use findstr.exe in a loop to show how many times each file contains the string, then filter for files with zero instances:

for /R %f in (filetypes) do find /C /I "searchtext" %f >> ..find.txt

(filetypes in this instance can be a space-separated list of possible file types.)