Magento - remove trailing slash from urls

For SEO reasons store owners will often want to standardise the URL generation in their Magento store. And rightly so, if your store is serving identical content at multiple urls then you could be penalised for having duplicate content on your site which will in turn negatively impact your search engine rankings.

To make sure you don't run into these problems with your Magento store, there are a few changes that are needed:

- Modify the method that creates URLs
- Fix some flawed Magento core logic
- Create an htaccess rewrite rule to remove manually added slashes

Firstly lets modify the getUrl() method to remove any trailing slashes in generated URLs. Copy the file app/code/core/Mage/Core/Block/Abstract.php to app/code/local/Mage/Core/Block/Abstract.php if it's not there already.

Open app/code/local/Mage/Core/Block/Abstract.php and find the getUrl() method, it should just be one line of code that returns the requested URL:

return $this->_getUrlModel()->getUrl($route, $params);

Replace that line with the following:

$return_url = $this->_getUrlModel()->getUrl($route, $params);
if ($return_url != $this->getBaseUrl() && substr($return_url, -1) == '/' && !Mage::getSingleton('admin/session')->isLoggedIn()):
    return substr($return_url, 0, -1);
else:
    return $return_url;
endif;

The above is pretty straignt forward stuff really, firstly we store the URL that would normally get returned from the method into the variable $return_url. We then run some tests to make sure firstly, the url we have is not for the homepage (in which case we do not want to remove the trailing slash), secondly it has a trailing slash as the last character, and thirdly we are not currently logged in to admin. When all three of these conditions are satisfied, we can remove the trailing slash from the end of the URL.

Now in theory that should be all we need to do, however there is, what I can only assume is some failed logic in another Magento core file that means this approach fails in some cases. To correct this, copy the file app/code/core/Mage/Core/Model/Url.php to app/code/local/Mage/Core/Model/Url.php if it's not there already.

Open app/code/local/Mage/Core/Model/Url.php and find the following:

if ($noSid !== true) {
    $this->_prepareSessionUrl($url);
}

A little further up the file the variable $noSid is initialised:

$noSid = null;

It is then set to either boolean true/false if certain conditions are met. If the conditions are not met, $noSid remains as null, the if statement is satisfied and the session id is appended to the URL (even though it should not be). In this case, what is actually returned is a session id of simply the letter U. The addition of this to the end of the URL means the first change we made will fail because the final character is not a slash.

So with the if statement above it seems logical that we only want to append the session id to the URL if $noSid is identically equal to false, thus ruling out null as a pass condition. So go ahead and change the if statement from:

if ($noSid !== true) {

to

if ($noSid === false) {

With this change, the session id will no longer be incorrectly added onto the URL and the first change we made to remove the trailing slash will succeed.

This should now remove all trailing slashes from generated URLs throughout the store, but a trailing slash can still be manually added to serve the same content. To cater for this scenario, we want to create a 301 redirect from all trailing slash URLs to a non trailing slash version of the page. We can do this in the Magento .htaccess file in the install root.

Open .htaccess and find the following rule:

RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]

Immediately after this add the following lines:

RewriteCond %{request_method} ^GET$
RewriteCond %{REQUEST_URI} !^/downloader.*$
RewriteCond %{REQUEST_URI} ^(.+)/$
RewriteRule ^(.+)$ %1 [L,R=301]

The redirect works in the following way. When requesting existing data from the server Magento will only ever use the GET method, and when sending new data to the server, POST will only ever be used (as is the standard). We never want to touch the POST requests (and indeed if you do you will find all kinds of problems like not being able to add to the basket, or even save anything in admin) so we restrict this rule to only ever affect GET requests - which is how pages will always be requested. The second line ensures the rule is not applied for Magento Connect Manager as this will break it. The third line ensures the rule is only ever applied to URLs with a trailing slash, and also stores all of the request URL up until that trailing slash into a back reference (the section in the brackets). With the conditions of the first three lines satisfied, the rule is then applied as a 301 redirect to the URL that has been stored in the RewriteCond backreference (so the url without the trailing slash). Note that if we wanted to redirect to the backreference in the RewriteRule we would use $1 instead of %1.

Integrating these changes will ensure your store never serves duplicate content caused by a trailing slash, and sets up a 301 redirect for any duplicate content already found by search engines.