Categories

Single Category Permalink

Author: Scott Reilly
Version: 2.5
First released: 2011-07-18
Last update: 2020-09-27
Compatibility: WP 4.6 – 5.5.1
Download: [ zip ]
Description:

Reduce permalinks (category or post) that include entire hierarchy of categories to just having the lowest level category.

Extended Description

Reduce permalinks (category or post) that include entire hierarchy of categories to just having the lowest category in the hierarchy.

By default, WordPress replaces the %category% permalink tag in a custom permalink structure with the entire hierarchy of categories for the post’s first matching category. For example, assuming your site has a hierarchical category structure like so:

Applications
  |_ Desktop
  |_ Web
    |_ WordPress

By default, if you have a permalink structure defined as %category%/%year%/%monthnum%/%day%/%postname%, your post titled “Best Plugins” assigned to the “WordPress” category would have a permalink of:

https://www.example.com/applications/web/wordpress/2008/01/15/best-plugins

If you activate the Single Category Permalink plugin, this would be the permalink generated for the post (and recognized by the blog):

https://www.example.com/wordpress/2008/01/15/best-plugins

In order for a category to be used as part of a post’s permalink structure, %category% must be explicitly defined in the Settings -> Permalinks admin page as part of a custom structure, i.e. /%category%/%postname%.

For category links, %category% is implied to follow the value set as the “Category base” (or the default category base if none is specified). So if your category base is ‘category’, the above example would list posts in the ‘WordPress’ category on this category listing page:

https://www.example.com/category/applications/web/wordpress/

With this plugin activated, that link would become:

https://www.example.com/category/wordpress/

NOTE: The fully hierarchical category and post permalinks will continue to work. The plugin issues a 302 redirect to browsers and search engines pointing them to the shorter URL.

Links: Plugin Homepage | Plugin Directory Page | GitHub | Author Homepage

Hooks

The plugin exposes one filter for hooking. Code using this filter should ideally be put into a mu-plugin or site-specific plugin (which is beyond the scope of this readme to explain). Less ideally, you could put them in your active theme’s functions.php file.

c2c_single_category_redirect_status (filter)

The ‘c2c_single_category_redirect_status’ hook allows you to specify an HTTP status code used for the redirect. By default this is 302.

Arguments:

  • $status (integer) : The default HTTP status code

Example:

/**
 * Change the redirection HTTP status to a 302.
 *
 * @param  int $code The HTTP status code. By default 301.
 * @return int
 */
function scp_change_redirect_status( $code ) {
    return 302;
}
add_filter( 'c2c_single_category_redirect_status', 'scp_change_redirect_status' );

Find out more at the plugin’s WordPress Plugin Repository page.

Installation

  1. Install via the built-in WordPress plugin installer. Or download and unzip single-category-permalinks.zip inside the plugins directory for your site (typically wp-content/plugins/)
  2. Activate the plugin through the ‘Plugins’ admin menu in WordPress
  3. Use %category% as a permalink tag in the Settings -> Permalinks admin options page when defining a custom permalink structure

Frequently Asked Questions

Q. Will existing links to my site that used the full category hierarchy still work?
A. Yes, WordPress will still serve the category listings and posts regardless of whether it is of the full category hierarchy format or just the single category format. But do note that WordPress doesn’t perform any sort of redirects; it responds directly to the category/post URL requested.

Q. Could this give the appearance that I have duplicate content on my site if pages are accessible via the full category hierarchy permalink format and the single category permalink format?
A. Whether this plugin is active or not, WordPress treats both types of category links the same. This plugin will however issue redirects for all of the non-canonical category and post permalink pages to point to the single category link version.

Q. What can this plugin do for me if I don’t use `%category%` in my custom permalink structure?
A. In addition to handling custom permalink structures (used to generate permalinks for posts) that contain %category%, the plugin also shortens category archive links. WordPress by default generates those links in a fully hierarchical fashion which this plugin will reduce to a single category. See the Description section for an example.

Q. Does this plugin include unit tests?
A. Yes.

Release Log

2.5 (2020-09-23)

  • Fix: Default the $taxonomy argument of category_link() to ‘category’ to avoid a PHP warning/error
  • Fix: Handle the possibility that get_category() could return null for an invalid category ID
  • New: Add a TODO item about removing deprecated functions (which is not something I want to do just yet, hence the TODO)
  • Change: Update docs for return value of category_link() to reflect that WP_Error or null are also possible values
  • Change: Note compatibility through WP 5.5+
  • Change: Restructure unit test file structure
    • New: Create new subdirectory phpunit/ to house all files related to unit testing
    • Change: Move bin/ to phpunit/bin/
    • Change: Move tests/bootstrap.php to phpunit/
    • Change: Move tests/ to phpunit/tests/
    • Change: Rename phpunit.xml to phpunit.xml.dist per best practices
  • Unit tests:
    • New: Add tests for category_link(), post_link()
    • New: Add unset_permalink_structures() to unset configured permalink structures

2.4.2 (2020-06-01)

  • Change: Use HTTPS for link to WP SVN repository in bin script for configuring unit tests (and remove commented-out code)
  • Change: Note compatibility through WP 5.4+
  • Change: Update links to coffee2code.com to be HTTPS
  • Change: Update URLs used in examples to be HTTPS
  • Change: Unit tests: Remove unnecessary unregistering of hooks

2.4.1 (2020-01-18)

  • Fix: Prevent interfering with permalinks for non-category taxonomies. Props mynameisrabby.

Copyright & Disclaimer

Copyright © 2011-2020 by Scott Reilly (aka coffee2code)

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

Discussion / Support

Have any questions, comments, or suggestions? Please provide them via the plugin’s WordPress.org support forum. I’ll do my best to reply in a timely fashion and help as best I can.

Unfortunately, I cannot provide guaranteed support, nor do I provide support via any other means.

Was this plugin useful useful to you? Consider giving it a rating. If you’re inclined to give it a poor rating, please first post to the support forum to give me a chance to address or explain the situation.

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