functions.md

NOTES

1. When initial code didn't work, I installed Debug Bar plugin and then not-yet-released Debug Bar Rewrite Rules plugin by Oleg Butuzov (who mailed it to me).

With the two plugins installed, click Debug link in admin bar, and in the popover select the Rewrite Rules tab. Now you'll see a list of all the rewrite rules in place on your site.

By comparing the regex, rewrite rules used for similar stuff (e.g. category archives, category archive pagination, category feeds, etc.) I was able to frame my own rules properly.

2. Resources

• http://wordpress.stackexchange.com/a/5478/10691

• http://wordpress.stackexchange.com/a/12577/10691

• http://wordpress.stackexchange.com/a/44207/10691

• http://wordpress.stackexchange.com/a/48513/10691

• http://wordpress.stackexchange.com/q/121434/10691

...use add_rewrite_rule() over messing directly with $wp_rewrite->rules if possible. The latter is a bit low-level.

— Stephen Harris

3. Related core files: /wp-includes/rewrite.php and /wp-includes/canonical.php

functions.php

<?php

function wtnerd_edition_specific_categories() {

	/*
	Rewrite e.g.:

	`example.com/?category_name=uk&channel=tech&feed=rss2` as `example.com/uk/channel/tech/feed/rss2/`

	`example.com/?category_name=uk&channel=tech&feed=rss2` as `example.com/uk/channel/tech/feed/`

	`example.com/?category_name=uk&channel=tech&paged=2` as `example.com/uk/channel/tech/page/2/`

	`example.com/?category_name=uk&channel=tech` as `example.com/uk/channel/tech/`
	*/

	add_rewrite_rule( '(.+?)/channel/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$', 'index.php?category_name=$matches[1]&channel=$matches[2]&feed=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/channel/(.+?)/(feed|rdf|rss|rss2|atom)/?$', 'index.php?category_name=$matches[1]&channel=$matches[2]&feed=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/channel/(.+?)/page/?([0-9]{1,})/?$', 'index.php?category_name=$matches[1]&channel=$matches[2]&paged=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/channel/(.+?)/?$', 'index.php?category_name=$matches[1]&channel=$matches[2]', 'top' );


	/*
	Rewrite e.g.:

	`example.com/?category_name=uk&tag=linux&feed=rss2` as `example.com/uk/section/linux/feed/rss2/`

	`example.com/?category_name=uk&tag=linux&feed=rss2` as `example.com/uk/section/linux/feed/`

	`example.com/?category_name=uk&tag=linux&paged=2` as `example.com/uk/section/linux/page/2/`

	`example.com/?category_name=uk&tag=linux` as `example.com/uk/section/linux/`
	*/

	add_rewrite_rule( '(.+?)/section/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$', 'index.php?category_name=$matches[1]&tag=$matches[2]&feed=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/section/(.+?)/(feed|rdf|rss|rss2|atom)/?$', 'index.php?category_name=$matches[1]&tag=$matches[2]&feed=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/section/(.+?)/page/?([0-9]{1,})/?$', 'index.php?category_name=$matches[1]&tag=$matches[2]&paged=$matches[3]', 'top' );

	add_rewrite_rule( '(.+?)/section/(.+?)/?$', 'index.php?category_name=$matches[1]&tag=$matches[2]', 'top' );
}
add_action( 'init', 'wtnerd_edition_specific_categories' );


// THE SAME CAN BE DONE LIKE THIS (BUT ABOVE METHOD IS RECOMMENDED)


function wtnerd_edition_specific_categories( $wp_rewrite ) {
	$rewrite_rules = array(
		'(.+?)/channel/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&channel='. $wp_rewrite->preg_index(2) .'&feed='. $wp_rewrite->preg_index(3),

		'(.+?)/channel/(.+?)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&channel='. $wp_rewrite->preg_index(2) .'&feed='. $wp_rewrite->preg_index(3),

		'(.+?)/channel/(.+?)/page/?([0-9]{1,})/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&channel='. $wp_rewrite->preg_index(2) .'&paged='. $wp_rewrite->preg_index(3),

		'(.+?)/channel/(.+?)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&channel='. $wp_rewrite->preg_index(2),

		'(.+?)/section/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&tag='. $wp_rewrite->preg_index(2) .'&feed='. $wp_rewrite->preg_index(3),

		'(.+?)/section/(.+?)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&tag='. $wp_rewrite->preg_index(2) .'&feed='. $wp_rewrite->preg_index(3),

		'(.+?)/section/(.+?)/page/?([0-9]{1,})/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&tag='. $wp_rewrite->preg_index(2) .'&paged='. $wp_rewrite->preg_index(3),

		'(.+?)/section/(.+?)/?$' => 'index.php?category_name='. $wp_rewrite->preg_index(1) .'&tag='. $wp_rewrite->preg_index(2)
	);
	$wp_rewrite->rules = $rewrite_rules + $wp_rewrite->rules;
}
add_filter( 'generate_rewrite_rules', 'wtnerd_edition_specific_categories' );


// OR LIKE THIS


function wtnerd_edition_specific_categories( $wp_rewrite ) {
	$rewrite_rules = array(
		'(.+?)/channel/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name=$matches[1]&channel=$matches[2]&feed=$matches[3]',
		'(.+?)/channel/(.+?)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name=$matches[1]&channel=$matches[2]&feed=$matches[3]',
		'(.+?)/channel/(.+?)/page/?([0-9]{1,})/?$' => 'index.php?category_name=$matches[1]&channel=$matches[2]&paged=$matches[3]',
		'(.+?)/channel/(.+?)/?$' => 'index.php?category_name=$matches[1]&channel=$matches[2]',

		'(.+?)/section/(.+?)/feed/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name=$matches[1]&tag=$matches[2]&feed=$matches[3]',
		'(.+?)/section/(.+?)/(feed|rdf|rss|rss2|atom)/?$' => 'index.php?category_name=$matches[1]&tag=$matches[2]&feed=$matches[3]',
		'(.+?)/section/(.+?)/page/?([0-9]{1,})/?$' => 'index.php?category_name=$matches[1]&tag=$matches[2]&paged=$matches[3]',
		'(.+?)/section/(.+?)/?$' => 'index.php?category_name=$matches[1]&tag=$matches[2]'
	);

	$wp_rewrite->rules = $rewrite_rules + $wp_rewrite->rules;
}
add_filter( 'generate_rewrite_rules', 'wtnerd_edition_specific_categories' );